diff --git a/perl/lib/Nix/Store.xs b/perl/lib/Nix/Store.xs
index f14c3f73f..ec85b844a 100644
--- a/perl/lib/Nix/Store.xs
+++ b/perl/lib/Nix/Store.xs
@@ -304,7 +304,10 @@ SV * derivationFromPath(char * drvPath)
 
             HV * outputs = newHV();
             for (auto & i : drv.outputs)
-                hv_store(outputs, i.first.c_str(), i.first.size(), newSVpv(store()->printStorePath(i.second.path).c_str(), 0), 0);
+                hv_store(
+                    outputs, i.first.c_str(), i.first.size(),
+                    newSVpv(store()->printStorePath(i.second.path(*store(), drv.name)).c_str(), 0),
+                    0);
             hv_stores(hash, "outputs", newRV((SV *) outputs));
 
             AV * inputDrvs = newAV();
diff --git a/src/libexpr/get-drvs.cc b/src/libexpr/get-drvs.cc
index 9055f59a1..5d6e39aa0 100644
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -39,7 +39,7 @@ DrvInfo::DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPat
     if (i == drv.outputs.end())
         throw Error("derivation '%s' does not have output '%s'", store->printStorePath(drvPath), outputName);
 
-    outPath = store->printStorePath(i->second.path);
+    outPath = store->printStorePath(i->second.path(*store, drv.name));
 }
 
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 9f877f765..ebe31724c 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -52,7 +52,7 @@ void EvalState::realiseContext(const PathSet & context)
                 DerivationOutputs::iterator i = drv.outputs.find(outputName);
                 if (i == drv.outputs.end())
                     throw Error("derivation '%s' does not have an output named '%s'", ctxS, outputName);
-                allowedPaths->insert(store->printStorePath(i->second.path));
+                allowedPaths->insert(store->printStorePath(i->second.path(*store, drv.name)));
             }
         }
     }
@@ -91,8 +91,17 @@ static void prim_scopedImport(EvalState & state, const Pos & pos, Value * * args
     Path realPath = state.checkSourcePath(state.toRealPath(path, context));
 
     // FIXME
-    if (state.store->isStorePath(path) && state.store->isValidPath(state.store->parseStorePath(path)) && isDerivation(path)) {
-        Derivation drv = readDerivation(*state.store, realPath);
+    auto isValidDerivationInStore = [&]() -> std::optional<StorePath> {
+        if (!state.store->isStorePath(path))
+            return std::nullopt;
+        auto storePath = state.store->parseStorePath(path);
+        if (!(state.store->isValidPath(storePath) && isDerivation(path)))
+            return std::nullopt;
+        return storePath;
+    };
+    if (auto optStorePath = isValidDerivationInStore()) {
+        auto storePath = *optStorePath;
+        Derivation drv = readDerivation(*state.store, realPath, Derivation::nameFromPath(storePath));
         Value & w = *state.allocValue();
         state.mkAttrs(w, 3 + drv.outputs.size());
         Value * v2 = state.allocAttr(w, state.sDrvPath);
@@ -106,7 +115,7 @@ static void prim_scopedImport(EvalState & state, const Pos & pos, Value * * args
 
         for (const auto & o : drv.outputs) {
             v2 = state.allocAttr(w, state.symbols.create(o.first));
-            mkString(*v2, state.store->printStorePath(o.second.path), {"!" + o.first + "!" + path});
+            mkString(*v2, state.store->printStorePath(o.second.path(*state.store, drv.name)), {"!" + o.first + "!" + path});
             outputsVal->listElems()[outputs_index] = state.allocValue();
             mkString(*(outputsVal->listElems()[outputs_index++]), o.first);
         }
@@ -570,6 +579,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
 
     /* Build the derivation expression by processing the attributes. */
     Derivation drv;
+    drv.name = drvName;
 
     PathSet context;
 
@@ -764,11 +774,12 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         auto outPath = state.store->makeFixedOutputPath(ingestionMethod, h, drvName);
         if (!jsonObject) drv.env["out"] = state.store->printStorePath(outPath);
         drv.outputs.insert_or_assign("out", DerivationOutput {
-            .path = std::move(outPath),
-            .hash = FixedOutputHash {
-                .method = ingestionMethod,
-                .hash = std::move(h),
-            },
+                .output = DerivationOutputFixed {
+                    .hash = FixedOutputHash {
+                        .method = ingestionMethod,
+                        .hash = std::move(h),
+                    },
+                },
         });
     }
 
@@ -783,8 +794,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             if (!jsonObject) drv.env[i] = "";
             drv.outputs.insert_or_assign(i,
                 DerivationOutput {
-                    .path = StorePath::dummy,
-                    .hash = std::optional<FixedOutputHash> {},
+                    .output = DerivationOutputInputAddressed {
+                        .path = StorePath::dummy,
+                    },
                 });
         }
 
@@ -795,8 +807,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             if (!jsonObject) drv.env[i] = state.store->printStorePath(outPath);
             drv.outputs.insert_or_assign(i,
                 DerivationOutput {
-                    .path = std::move(outPath),
-                    .hash = std::optional<FixedOutputHash>(),
+                    .output = DerivationOutputInputAddressed {
+                        .path = std::move(outPath),
+                    },
                 });
         }
     }
@@ -817,7 +830,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     mkString(*state.allocAttr(v, state.sDrvPath), drvPathS, {"=" + drvPathS});
     for (auto & i : drv.outputs) {
         mkString(*state.allocAttr(v, state.symbols.create(i.first)),
-            state.store->printStorePath(i.second.path), {"!" + i.first + "!" + drvPathS});
+            state.store->printStorePath(i.second.path(*state.store, drv.name)), {"!" + i.first + "!" + drvPathS});
     }
     v.attrs->sort();
 }
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 62294a08c..109368f8a 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1047,7 +1047,7 @@ DerivationGoal::DerivationGoal(const StorePath & drvPath, const BasicDerivation
 {
     this->drv = std::make_unique<BasicDerivation>(BasicDerivation(drv));
     state = &DerivationGoal::haveDerivation;
-    name = fmt("building of %s", worker.store.showPaths(drv.outputPaths()));
+    name = fmt("building of %s", worker.store.showPaths(drv.outputPaths(worker.store)));
     trace("created");
 
     mcExpectedBuilds = std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds);
@@ -1182,7 +1182,7 @@ void DerivationGoal::haveDerivation()
     retrySubstitution = false;
 
     for (auto & i : drv->outputs)
-        worker.store.addTempRoot(i.second.path);
+        worker.store.addTempRoot(i.second.path(worker.store, drv->name));
 
     /* Check what outputs paths are not already valid. */
     auto invalidOutputs = checkPathValidity(false, buildMode == bmRepair);
@@ -1290,12 +1290,12 @@ void DerivationGoal::repairClosure()
     StorePathSet outputClosure;
     for (auto & i : drv->outputs) {
         if (!wantOutput(i.first, wantedOutputs)) continue;
-        worker.store.computeFSClosure(i.second.path, outputClosure);
+        worker.store.computeFSClosure(i.second.path(worker.store, drv->name), outputClosure);
     }
 
     /* Filter out our own outputs (which we have already checked). */
     for (auto & i : drv->outputs)
-        outputClosure.erase(i.second.path);
+        outputClosure.erase(i.second.path(worker.store, drv->name));
 
     /* Get all dependencies of this derivation so that we know which
        derivation is responsible for which path in the output
@@ -1307,7 +1307,7 @@ void DerivationGoal::repairClosure()
         if (i.isDerivation()) {
             Derivation drv = worker.store.derivationFromPath(i);
             for (auto & j : drv.outputs)
-                outputsToDrv.insert_or_assign(j.second.path, i);
+                outputsToDrv.insert_or_assign(j.second.path(worker.store, drv.name), i);
         }
 
     /* Check each path (slow!). */
@@ -1379,7 +1379,7 @@ void DerivationGoal::inputsRealised()
             for (auto & j : i.second) {
                 auto k = inDrv.outputs.find(j);
                 if (k != inDrv.outputs.end())
-                    worker.store.computeFSClosure(k->second.path, inputPaths);
+                    worker.store.computeFSClosure(k->second.path(worker.store, inDrv.name), inputPaths);
                 else
                     throw Error(
                         "derivation '%s' requires non-existent output '%s' from input derivation '%s'",
@@ -1432,7 +1432,7 @@ void DerivationGoal::tryToBuild()
        goal can start a build, and if not, the main loop will sleep a
        few seconds and then retry this goal. */
     PathSet lockFiles;
-    for (auto & outPath : drv->outputPaths())
+    for (auto & outPath : drv->outputPaths(worker.store))
         lockFiles.insert(worker.store.Store::toRealPath(outPath));
 
     if (!outputLocks.lockPaths(lockFiles, "", false)) {
@@ -1460,16 +1460,16 @@ void DerivationGoal::tryToBuild()
         return;
     }
 
-    missingPaths = drv->outputPaths();
+    missingPaths = drv->outputPaths(worker.store);
     if (buildMode != bmCheck)
         for (auto & i : validPaths) missingPaths.erase(i);
 
     /* If any of the outputs already exist but are not valid, delete
        them. */
     for (auto & i : drv->outputs) {
-        if (worker.store.isValidPath(i.second.path)) continue;
-        debug("removing invalid path '%s'", worker.store.printStorePath(i.second.path));
-        deletePath(worker.store.Store::toRealPath(i.second.path));
+        if (worker.store.isValidPath(i.second.path(worker.store, drv->name))) continue;
+        debug("removing invalid path '%s'", worker.store.printStorePath(i.second.path(worker.store, drv->name)));
+        deletePath(worker.store.Store::toRealPath(i.second.path(worker.store, drv->name)));
     }
 
     /* Don't do a remote build if the derivation has the attribute
@@ -1692,7 +1692,7 @@ void DerivationGoal::buildDone()
                 fmt("running post-build-hook '%s'", settings.postBuildHook),
                 Logger::Fields{worker.store.printStorePath(drvPath)});
             PushActivity pact(act.id);
-            auto outputPaths = drv->outputPaths();
+            auto outputPaths = drv->outputPaths(worker.store);
             std::map<std::string, std::string> hookEnvironment = getEnv();
 
             hookEnvironment.emplace("DRV_PATH", worker.store.printStorePath(drvPath));
@@ -1920,7 +1920,7 @@ StorePathSet DerivationGoal::exportReferences(const StorePathSet & storePaths)
         if (j.isDerivation()) {
             Derivation drv = worker.store.derivationFromPath(j);
             for (auto & k : drv.outputs)
-                worker.store.computeFSClosure(k.second.path, paths);
+                worker.store.computeFSClosure(k.second.path(worker.store, drv.name), paths);
         }
     }
 
@@ -2015,7 +2015,7 @@ void DerivationGoal::startBuilder()
 
     /* Substitute output placeholders with the actual output paths. */
     for (auto & output : drv->outputs)
-        inputRewrites[hashPlaceholder(output.first)] = worker.store.printStorePath(output.second.path);
+        inputRewrites[hashPlaceholder(output.first)] = worker.store.printStorePath(output.second.path(worker.store, drv->name));
 
     /* Construct the environment passed to the builder. */
     initEnv();
@@ -2200,7 +2200,7 @@ void DerivationGoal::startBuilder()
            (typically the dependencies of /bin/sh).  Throw them
            out. */
         for (auto & i : drv->outputs)
-            dirsInChroot.erase(worker.store.printStorePath(i.second.path));
+            dirsInChroot.erase(worker.store.printStorePath(i.second.path(worker.store, drv->name)));
 
 #elif __APPLE__
         /* We don't really have any parent prep work to do (yet?)
@@ -2613,7 +2613,7 @@ void DerivationGoal::writeStructuredAttrs()
     /* Add an "outputs" object containing the output paths. */
     nlohmann::json outputs;
     for (auto & i : drv->outputs)
-        outputs[i.first] = rewriteStrings(worker.store.printStorePath(i.second.path), inputRewrites);
+        outputs[i.first] = rewriteStrings(worker.store.printStorePath(i.second.path(worker.store, drv->name)), inputRewrites);
     json["outputs"] = outputs;
 
     /* Handle exportReferencesGraph. */
@@ -2817,7 +2817,7 @@ struct RestrictedStore : public LocalFSStore
                 auto drv = derivationFromPath(path.path);
                 for (auto & output : drv.outputs)
                     if (wantOutput(output.first, path.outputs))
-                        newPaths.insert(output.second.path);
+                        newPaths.insert(output.second.path(*this, drv.name));
             } else if (!goal.isAllowed(path.path))
                 throw InvalidPath("cannot build unknown path '%s' in recursive Nix", printStorePath(path.path));
         }
@@ -3579,7 +3579,7 @@ StorePathSet parseReferenceSpecifiers(Store & store, const BasicDerivation & drv
         if (store.isStorePath(i))
             result.insert(store.parseStorePath(i));
         else if (drv.outputs.count(i))
-            result.insert(drv.outputs.find(i)->second.path);
+            result.insert(drv.outputs.find(i)->second.path(store, drv.name));
         else throw BuildError("derivation contains an illegal reference specifier '%s'", i);
     }
     return result;
@@ -3617,7 +3617,7 @@ void DerivationGoal::registerOutputs()
     if (hook) {
         bool allValid = true;
         for (auto & i : drv->outputs)
-            if (!worker.store.isValidPath(i.second.path)) allValid = false;
+            if (!worker.store.isValidPath(i.second.path(worker.store, drv->name))) allValid = false;
         if (allValid) return;
     }
 
@@ -3638,23 +3638,23 @@ void DerivationGoal::registerOutputs()
        Nix calls. */
     StorePathSet referenceablePaths;
     for (auto & p : inputPaths) referenceablePaths.insert(p);
-    for (auto & i : drv->outputs) referenceablePaths.insert(i.second.path);
+    for (auto & i : drv->outputs) referenceablePaths.insert(i.second.path(worker.store, drv->name));
     for (auto & p : addedPaths) referenceablePaths.insert(p);
 
     /* Check whether the output paths were created, and grep each
        output path to determine what other paths it references.  Also make all
        output paths read-only. */
     for (auto & i : drv->outputs) {
-        auto path = worker.store.printStorePath(i.second.path);
-        if (!missingPaths.count(i.second.path)) continue;
+        auto path = worker.store.printStorePath(i.second.path(worker.store, drv->name));
+        if (!missingPaths.count(i.second.path(worker.store, drv->name))) continue;
 
         Path actualPath = path;
         if (needsHashRewrite()) {
-            auto r = redirectedOutputs.find(i.second.path);
+            auto r = redirectedOutputs.find(i.second.path(worker.store, drv->name));
             if (r != redirectedOutputs.end()) {
                 auto redirected = worker.store.Store::toRealPath(r->second);
                 if (buildMode == bmRepair
-                    && redirectedBadOutputs.count(i.second.path)
+                    && redirectedBadOutputs.count(i.second.path(worker.store, drv->name))
                     && pathExists(redirected))
                     replaceValidPath(path, redirected);
                 if (buildMode == bmCheck)
@@ -3723,7 +3723,9 @@ void DerivationGoal::registerOutputs()
 
         if (fixedOutput) {
 
-            if (i.second.hash->method == FileIngestionMethod::Flat) {
+            FixedOutputHash outputHash = std::get<DerivationOutputFixed>(i.second.output).hash;
+
+            if (outputHash.method == FileIngestionMethod::Flat) {
                 /* The output path should be a regular file without execute permission. */
                 if (!S_ISREG(st.st_mode) || (st.st_mode & S_IXUSR) != 0)
                     throw BuildError(
@@ -3734,13 +3736,13 @@ void DerivationGoal::registerOutputs()
 
             /* Check the hash. In hash mode, move the path produced by
                the derivation to its content-addressed location. */
-            Hash h2 = i.second.hash->method == FileIngestionMethod::Recursive
-                ? hashPath(*i.second.hash->hash.type, actualPath).first
-                : hashFile(*i.second.hash->hash.type, actualPath);
+            Hash h2 = outputHash.method == FileIngestionMethod::Recursive
+                ? hashPath(*outputHash.hash.type, actualPath).first
+                : hashFile(*outputHash.hash.type, actualPath);
 
-            auto dest = worker.store.makeFixedOutputPath(i.second.hash->method, h2, i.second.path.name());
+            auto dest = worker.store.makeFixedOutputPath(outputHash.method, h2, i.second.path(worker.store, drv->name).name());
 
-            if (i.second.hash->hash != h2) {
+            if (outputHash.hash != h2) {
 
                 /* Throw an error after registering the path as
                    valid. */
@@ -3748,7 +3750,7 @@ void DerivationGoal::registerOutputs()
                 delayedException = std::make_exception_ptr(
                     BuildError("hash mismatch in fixed-output derivation '%s':\n  wanted: %s\n  got:    %s",
                         worker.store.printStorePath(dest),
-                        i.second.hash->hash.to_string(SRI, true),
+                        outputHash.hash.to_string(SRI, true),
                         h2.to_string(SRI, true)));
 
                 Path actualDest = worker.store.Store::toRealPath(dest);
@@ -3770,7 +3772,7 @@ void DerivationGoal::registerOutputs()
                 assert(worker.store.parseStorePath(path) == dest);
 
             ca = FixedOutputHash {
-                .method = i.second.hash->method,
+                .method = outputHash.method,
                 .hash = h2,
             };
         }
@@ -3894,7 +3896,7 @@ void DerivationGoal::registerOutputs()
     /* If this is the first round of several, then move the output out of the way. */
     if (nrRounds > 1 && curRound == 1 && curRound < nrRounds && keepPreviousRound) {
         for (auto & i : drv->outputs) {
-            auto path = worker.store.printStorePath(i.second.path);
+            auto path = worker.store.printStorePath(i.second.path(worker.store, drv->name));
             Path prev = path + checkSuffix;
             deletePath(prev);
             Path dst = path + checkSuffix;
@@ -3912,7 +3914,7 @@ void DerivationGoal::registerOutputs()
        if the result was not determistic? */
     if (curRound == nrRounds) {
         for (auto & i : drv->outputs) {
-            Path prev = worker.store.printStorePath(i.second.path) + checkSuffix;
+            Path prev = worker.store.printStorePath(i.second.path(worker.store, drv->name)) + checkSuffix;
             deletePath(prev);
         }
     }
@@ -4213,9 +4215,9 @@ StorePathSet DerivationGoal::checkPathValidity(bool returnValid, bool checkHash)
     for (auto & i : drv->outputs) {
         if (!wantOutput(i.first, wantedOutputs)) continue;
         bool good =
-            worker.store.isValidPath(i.second.path) &&
-            (!checkHash || worker.pathContentsGood(i.second.path));
-        if (good == returnValid) result.insert(i.second.path);
+            worker.store.isValidPath(i.second.path(worker.store, drv->name)) &&
+            (!checkHash || worker.pathContentsGood(i.second.path(worker.store, drv->name)));
+        if (good == returnValid) result.insert(i.second.path(worker.store, drv->name));
     }
     return result;
 }
diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index e630cf6f1..017a633b5 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -63,16 +63,19 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
     auto & output = drv.outputs.begin()->second;
 
     /* Try the hashed mirrors first. */
-    if (output.hash && output.hash->method == FileIngestionMethod::Flat)
-        for (auto hashedMirror : settings.hashedMirrors.get())
-            try {
-                if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
-                auto & h = output.hash->hash;
-                fetch(hashedMirror + printHashType(*h.type) + "/" + h.to_string(Base16, false));
-                return;
-            } catch (Error & e) {
-                debug(e.what());
+    if (auto hash = std::get_if<DerivationOutputFixed>(&output.output)) {
+        if (hash->hash.method == FileIngestionMethod::Flat) {
+            for (auto hashedMirror : settings.hashedMirrors.get()) {
+                try {
+                    if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
+                    fetch(hashedMirror + printHashType(*hash->hash.hash.type) + "/" + hash->hash.hash.to_string(Base16, false));
+                    return;
+                } catch (Error & e) {
+                    debug(e.what());
+                }
             }
+        }
+    }
 
     /* Otherwise try the specified URL. */
     fetch(mainUrl);
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 7e16529a5..df295084a 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -451,7 +451,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopBuildDerivation: {
         auto drvPath = store->parseStorePath(readString(from));
         BasicDerivation drv;
-        readDerivation(from, *store, drv);
+        readDerivation(from, *store, drv, Derivation::nameFromPath(drvPath));
         BuildMode buildMode = (BuildMode) readInt(from);
         logger->startWork();
         if (!trusted)
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 870901421..7d0a5abeb 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -7,6 +7,22 @@
 
 namespace nix {
 
+// FIXME Put this somewhere?
+template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
+template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
+
+StorePath DerivationOutput::path(const Store & store, std::string_view drvName) const
+{
+    return std::visit(overloaded {
+        [](DerivationOutputInputAddressed doi) {
+            return doi.path;
+        },
+        [&](DerivationOutputFixed dof) {
+            return store.makeFixedOutputPath(dof.hash.method, dof.hash.hash, drvName);
+        }
+    }, output);
+}
+
 
 bool BasicDerivation::isBuiltin() const
 {
@@ -99,7 +115,6 @@ static DerivationOutput parseDerivationOutput(const Store & store, std::istrings
     expect(str, ","); const auto hash = parseString(str);
     expect(str, ")");
 
-    std::optional<FixedOutputHash> fsh;
     if (hashAlgo != "") {
         auto method = FileIngestionMethod::Flat;
         if (string(hashAlgo, 0, 2) == "r:") {
@@ -107,22 +122,29 @@ static DerivationOutput parseDerivationOutput(const Store & store, std::istrings
             hashAlgo = string(hashAlgo, 2);
         }
         const HashType hashType = parseHashType(hashAlgo);
-        fsh = FixedOutputHash {
-            .method = std::move(method),
-            .hash = Hash(hash, hashType),
-        };
-    }
 
-    return DerivationOutput {
-        .path = std::move(path),
-        .hash = std::move(fsh),
-    };
+        return DerivationOutput {
+            .output = DerivationOutputFixed {
+                .hash = FixedOutputHash {
+                    .method = std::move(method),
+                    .hash = Hash(hash, hashType),
+                },
+            }
+        };
+    } else
+        return DerivationOutput {
+            .output = DerivationOutputInputAddressed {
+                .path = std::move(path),
+            }
+        };
 }
 
 
-static Derivation parseDerivation(const Store & store, std::string && s)
+static Derivation parseDerivation(const Store & store, std::string && s, std::string_view name)
 {
     Derivation drv;
+    drv.name = name;
+
     std::istringstream str(std::move(s));
     expect(str, "Derive([");
 
@@ -166,10 +188,10 @@ static Derivation parseDerivation(const Store & store, std::string && s)
 }
 
 
-Derivation readDerivation(const Store & store, const Path & drvPath)
+Derivation readDerivation(const Store & store, const Path & drvPath, std::string_view name)
 {
     try {
-        return parseDerivation(store, readFile(drvPath));
+        return parseDerivation(store, readFile(drvPath), name);
     } catch (FormatError & e) {
         throw Error("error parsing derivation '%1%': %2%", drvPath, e.msg());
     }
@@ -187,7 +209,7 @@ Derivation Store::readDerivation(const StorePath & drvPath)
 {
     auto accessor = getFSAccessor();
     try {
-        return parseDerivation(*this, accessor->readFile(printStorePath(drvPath)));
+        return parseDerivation(*this, accessor->readFile(printStorePath(drvPath)), Derivation::nameFromPath(drvPath));
     } catch (FormatError & e) {
         throw Error("error parsing derivation '%s': %s", printStorePath(drvPath), e.msg());
     }
@@ -255,10 +277,14 @@ string Derivation::unparse(const Store & store, bool maskOutputs,
     for (auto & i : outputs) {
         if (first) first = false; else s += ',';
         s += '('; printUnquotedString(s, i.first);
-        s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(i.second.path));
-        s += ','; printUnquotedString(s, i.second.hash ? i.second.hash->printMethodAlgo() : "");
-        s += ','; printUnquotedString(s,
-            i.second.hash ? i.second.hash->hash.to_string(Base16, false) : "");
+        s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(i.second.path(store, name)));
+        if (auto hash = std::get_if<DerivationOutputFixed>(&i.second.output)) {
+            s += ','; printUnquotedString(s, hash->hash.printMethodAlgo());
+            s += ','; printUnquotedString(s, hash->hash.hash.to_string(Base16, false));
+        } else {
+            s += ','; printUnquotedString(s, "");
+            s += ','; printUnquotedString(s, "");
+        }
         s += ')';
     }
 
@@ -314,7 +340,7 @@ bool BasicDerivation::isFixedOutput() const
 {
     return outputs.size() == 1 &&
         outputs.begin()->first == "out" &&
-        outputs.begin()->second.hash;
+        std::holds_alternative<DerivationOutputFixed>(outputs.begin()->second.output);
 }
 
 
@@ -346,10 +372,11 @@ Hash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOutput
     /* Return a fixed hash for fixed-output derivations. */
     if (drv.isFixedOutput()) {
         DerivationOutputs::const_iterator i = drv.outputs.begin();
+        auto hash = std::get<DerivationOutputFixed>(i->second.output);
         return hashString(htSHA256, "fixed:out:"
-            + i->second.hash->printMethodAlgo() + ":"
-            + i->second.hash->hash.to_string(Base16, false) + ":"
-            + store.printStorePath(i->second.path));
+            + hash.hash.printMethodAlgo() + ":"
+            + hash.hash.hash.to_string(Base16, false) + ":"
+            + store.printStorePath(i->second.path(store, drv.name)));
     }
 
     /* For other derivations, replace the inputs paths with recursive
@@ -383,11 +410,11 @@ bool wantOutput(const string & output, const std::set<string> & wanted)
 }
 
 
-StorePathSet BasicDerivation::outputPaths() const
+StorePathSet BasicDerivation::outputPaths(const Store & store) const
 {
     StorePathSet paths;
     for (auto & i : outputs)
-        paths.insert(i.second.path);
+        paths.insert(i.second.path(store, name));
     return paths;
 }
 
@@ -397,7 +424,6 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
     auto hashAlgo = readString(in);
     auto hash = readString(in);
 
-    std::optional<FixedOutputHash> fsh;
     if (hashAlgo != "") {
         auto method = FileIngestionMethod::Flat;
         if (string(hashAlgo, 0, 2) == "r:") {
@@ -405,16 +431,20 @@ static DerivationOutput readDerivationOutput(Source & in, const Store & store)
             hashAlgo = string(hashAlgo, 2);
         }
         auto hashType = parseHashType(hashAlgo);
-        fsh = FixedOutputHash {
-            .method = std::move(method),
-            .hash = Hash(hash, hashType),
+        return DerivationOutput {
+            .output = DerivationOutputFixed {
+                .hash = FixedOutputHash {
+                    .method = std::move(method),
+                    .hash = Hash(hash, hashType),
+                },
+            }
+        };
+    } else
+        return DerivationOutput {
+            .output = DerivationOutputInputAddressed {
+                .path = std::move(path),
+            }
         };
-    }
-
-    return DerivationOutput {
-        .path = std::move(path),
-        .hash = std::move(fsh),
-    };
 }
 
 StringSet BasicDerivation::outputNames() const
@@ -426,8 +456,19 @@ StringSet BasicDerivation::outputNames() const
 }
 
 
-Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv)
+std::string_view BasicDerivation::nameFromPath(const StorePath & drvPath) {
+    auto nameWithSuffix = drvPath.name();
+    constexpr std::string_view extension = ".drv";
+    assert(hasSuffix(nameWithSuffix, extension));
+    nameWithSuffix.remove_suffix(extension.size());
+    return nameWithSuffix;
+}
+
+
+Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv, std::string_view name)
 {
+    drv.name = name;
+
     drv.outputs.clear();
     auto nr = readNum<size_t>(in);
     for (size_t n = 0; n < nr; n++) {
@@ -456,10 +497,10 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
     out << drv.outputs.size();
     for (auto & i : drv.outputs) {
         out << i.first
-            << store.printStorePath(i.second.path);
-        if (i.second.hash) {
-            out << i.second.hash->printMethodAlgo()
-                << i.second.hash->hash.to_string(Base16, false);
+            << store.printStorePath(i.second.path(store, drv.name));
+        if (auto hash = std::get_if<DerivationOutputFixed>(&i.second.output)) {
+            out << hash->hash.printMethodAlgo()
+                << hash->hash.hash.to_string(Base16, false);
         } else {
             out << "" << "";
         }
diff --git a/src/libstore/derivations.hh b/src/libstore/derivations.hh
index 00cf1bb08..133ffe50e 100644
--- a/src/libstore/derivations.hh
+++ b/src/libstore/derivations.hh
@@ -13,10 +13,20 @@ namespace nix {
 
 /* Abstract syntax of derivations. */
 
-struct DerivationOutput
+struct DerivationOutputInputAddressed
 {
     StorePath path;
-    std::optional<FixedOutputHash> hash; /* hash used for expected hash computation */
+};
+
+struct DerivationOutputFixed
+{
+    FixedOutputHash hash; /* hash used for expected hash computation */
+};
+
+struct DerivationOutput
+{
+    std::variant<DerivationOutputInputAddressed, DerivationOutputFixed> output;
+    StorePath path(const Store & store, std::string_view drvName) const;
 };
 
 typedef std::map<string, DerivationOutput> DerivationOutputs;
@@ -35,6 +45,7 @@ struct BasicDerivation
     Path builder;
     Strings args;
     StringPairs env;
+    std::string name;
 
     BasicDerivation() { }
     virtual ~BasicDerivation() { };
@@ -45,10 +56,12 @@ struct BasicDerivation
     bool isFixedOutput() const;
 
     /* Return the output paths of a derivation. */
-    StorePathSet outputPaths() const;
+    StorePathSet outputPaths(const Store & store) const;
 
     /* Return the output names of a derivation. */
     StringSet outputNames() const;
+
+    static std::string_view nameFromPath(const StorePath & storePath);
 };
 
 struct Derivation : BasicDerivation
@@ -72,7 +85,7 @@ StorePath writeDerivation(ref<Store> store,
     const Derivation & drv, std::string_view name, RepairFlag repair = NoRepair);
 
 /* Read a derivation from a file. */
-Derivation readDerivation(const Store & store, const Path & drvPath);
+Derivation readDerivation(const Store & store, const Path & drvPath, std::string_view name);
 
 // FIXME: remove
 bool isDerivation(const string & fileName);
@@ -89,7 +102,7 @@ bool wantOutput(const string & output, const std::set<string> & wanted);
 struct Source;
 struct Sink;
 
-Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv);
+Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv, std::string_view name);
 void writeDerivation(Sink & out, const Store & store, const BasicDerivation & drv);
 
 std::string hashPlaceholder(const std::string & outputName);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 9ea71170f..1e6b34cd1 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -560,19 +560,12 @@ void LocalStore::checkDerivationOutputs(const StorePath & drvPath, const Derivat
         DerivationOutputs::const_iterator out = drv.outputs.find("out");
         if (out == drv.outputs.end())
             throw Error("derivation '%s' does not have an output named 'out'", printStorePath(drvPath));
-
-        check(
-            makeFixedOutputPath(
-                out->second.hash->method,
-                out->second.hash->hash,
-                drvName),
-            out->second.path, "out");
     }
 
     else {
         Hash h = hashDerivationModulo(*this, drv, true);
         for (auto & i : drv.outputs)
-            check(makeOutputPath(i.first, h, drvName), i.second.path, i.first);
+            check(makeOutputPath(i.first, h, drvName), i.second.path(*this, drv.name), i.first);
     }
 }
 
@@ -614,7 +607,7 @@ uint64_t LocalStore::addValidPath(State & state,
             state.stmtAddDerivationOutput.use()
                 (id)
                 (i.first)
-                (printStorePath(i.second.path))
+                (printStorePath(i.second.path(*this, drv.name)))
                 .exec();
         }
     }
diff --git a/src/libstore/misc.cc b/src/libstore/misc.cc
index e68edb38c..c4d22a634 100644
--- a/src/libstore/misc.cc
+++ b/src/libstore/misc.cc
@@ -198,8 +198,8 @@ void Store::queryMissing(const std::vector<StorePathWithOutputs> & targets,
             PathSet invalid;
             for (auto & j : drv->outputs)
                 if (wantOutput(j.first, path.outputs)
-                    && !isValidPath(j.second.path))
-                    invalid.insert(printStorePath(j.second.path));
+                    && !isValidPath(j.second.path(*this, drv->name)))
+                    invalid.insert(printStorePath(j.second.path(*this, drv->name)));
             if (invalid.empty()) return;
 
             if (settings.useSubstitutes && parsedDrv.substitutesAllowed()) {
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 23bb48d88..9c8874fd4 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -77,7 +77,7 @@ static PathSet realisePath(StorePathWithOutputs path, bool build = true)
             if (i == drv.outputs.end())
                 throw Error("derivation '%s' does not have an output named '%s'",
                     store2->printStorePath(path.path), j);
-            auto outPath = store2->printStorePath(i->second.path);
+            auto outPath = store2->printStorePath(i->second.path(*store, drv.name));
             if (store2) {
                 if (gcRoot == "")
                     printGCWarning();
@@ -219,7 +219,7 @@ static StorePathSet maybeUseOutputs(const StorePath & storePath, bool useOutput,
         auto drv = store->derivationFromPath(storePath);
         StorePathSet outputs;
         for (auto & i : drv.outputs)
-            outputs.insert(i.second.path);
+            outputs.insert(i.second.path(*store, drv.name));
         return outputs;
     }
     else return {storePath};
@@ -313,7 +313,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
                 if (forceRealise) realisePath({i2});
                 Derivation drv = store->derivationFromPath(i2);
                 for (auto & j : drv.outputs)
-                    cout << fmt("%1%\n", store->printStorePath(j.second.path));
+                    cout << fmt("%1%\n", store->printStorePath(j.second.path(*store, drv.name)));
             }
             break;
         }
@@ -914,9 +914,9 @@ static void opServe(Strings opFlags, Strings opArgs)
 
                 if (!writeAllowed) throw Error("building paths is not allowed");
 
-                auto drvPath = store->parseStorePath(readString(in)); // informational only
+                auto drvPath = store->parseStorePath(readString(in));
                 BasicDerivation drv;
-                readDerivation(in, *store, drv);
+                readDerivation(in, *store, drv, Derivation::nameFromPath(drvPath));
 
                 getBuildSettings();
 
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index a6d7d6add..2f590f53f 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -130,14 +130,16 @@ StorePath getDerivationEnvironment(ref<Store> store, const StorePath & drvPath)
     drvName += "-env";
     for (auto & output : drv.outputs)
         drv.env.erase(output.first);
-    drv.outputs = {{"out", DerivationOutput { .path = StorePath::dummy }}};
+    drv.outputs = {{"out", DerivationOutput { .output = DerivationOutputInputAddressed { .path = StorePath::dummy }}}};
     drv.env["out"] = "";
     drv.env["_outputs_saved"] = drv.env["outputs"];
     drv.env["outputs"] = "out";
     drv.inputSrcs.insert(std::move(getEnvShPath));
     Hash h = hashDerivationModulo(*store, drv, true);
     auto shellOutPath = store->makeOutputPath("out", h, drvName);
-    drv.outputs.insert_or_assign("out", DerivationOutput { .path = shellOutPath });
+    drv.outputs.insert_or_assign("out", DerivationOutput { .output = DerivationOutputInputAddressed {
+                .path = shellOutPath
+            } });
     drv.env["out"] = store->printStorePath(shellOutPath);
     auto shellDrvPath2 = writeDerivation(store, drv, drvName);
 
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index a13e5a3df..b245e417e 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -304,8 +304,9 @@ struct InstallableStorePath : Installable
     {
         if (storePath.isDerivation()) {
             std::map<std::string, StorePath> outputs;
-            for (auto & [name, output] : store->readDerivation(storePath).outputs)
-                outputs.emplace(name, output.path);
+            auto drv = store->readDerivation(storePath);
+            for (auto & [name, output] : drv.outputs)
+                outputs.emplace(name, output.path(*store, drv.name));
             return {
                 Buildable {
                     .drvPath = storePath,
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 8eb58f62a..fb9050d0d 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -483,10 +483,10 @@ bool NixRepl::processLine(string line)
                but doing it in a child makes it easier to recover from
                problems / SIGINT. */
             if (runProgram(settings.nixBinDir + "/nix", Strings{"build", "--no-link", drvPath}) == 0) {
-                auto drv = readDerivation(*state->store, drvPath);
+                auto drv = readDerivation(*state->store, drvPath, Derivation::nameFromPath(state->store->parseStorePath(drvPath)));
                 std::cout << std::endl << "this derivation produced the following outputs:" << std::endl;
                 for (auto & i : drv.outputs)
-                    std::cout << fmt("  %s -> %s\n", i.first, state->store->printStorePath(i.second.path));
+                    std::cout << fmt("  %s -> %s\n", i.first, state->store->printStorePath(i.second.path(*state->store, drv.name)));
             }
         } else if (command == ":i") {
             runProgram(settings.nixBinDir + "/nix-env", Strings{"-i", drvPath});
diff --git a/src/nix/show-derivation.cc b/src/nix/show-derivation.cc
index b5434f982..9fd26e2d7 100644
--- a/src/nix/show-derivation.cc
+++ b/src/nix/show-derivation.cc
@@ -69,10 +69,10 @@ struct CmdShowDerivation : InstallablesCommand
                 auto outputsObj(drvObj.object("outputs"));
                 for (auto & output : drv.outputs) {
                     auto outputObj(outputsObj.object(output.first));
-                    outputObj.attr("path", store->printStorePath(output.second.path));
-                    if (output.second.hash) {
-                        outputObj.attr("hashAlgo", output.second.hash->printMethodAlgo());
-                        outputObj.attr("hash", output.second.hash->hash.to_string(Base16, false));
+                    outputObj.attr("path", store->printStorePath(output.second.path(*store, drv.name)));
+                    if (auto hash = std::get_if<DerivationOutputFixed>(&output.second.output)) {
+                        outputObj.attr("hashAlgo", hash->hash.printMethodAlgo());
+                        outputObj.attr("hash", hash->hash.hash.to_string(Base16, false));
                     }
                 }
             }