diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index ab51c229d..bedf11e2c 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -165,7 +165,7 @@ BuiltPathsCommand::BuiltPathsCommand(bool recursive)
     });
 }
 
-void BuiltPathsCommand::run(ref<Store> store)
+void BuiltPathsCommand::run(ref<Store> store, Installables && installables)
 {
     BuiltPaths paths;
     if (all) {
@@ -211,7 +211,7 @@ void StorePathsCommand::run(ref<Store> store, BuiltPaths && paths)
     run(store, std::move(sorted));
 }
 
-void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePaths)
+void StorePathCommand::run(ref<Store> store, StorePaths && storePaths)
 {
     if (storePaths.size() != 1)
         throw UsageError("this command requires exactly one store path");
@@ -246,7 +246,7 @@ void MixProfile::updateProfile(const BuiltPaths & buildables)
 {
     if (!profile) return;
 
-    std::vector<StorePath> result;
+    StorePaths result;
 
     for (auto & buildable : buildables) {
         std::visit(overloaded {
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 0d84c8395..874ca3249 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -29,6 +29,9 @@ struct NixMultiCommand : virtual MultiCommand, virtual Command
     nlohmann::json toJSON() override;
 };
 
+// For the overloaded run methods
+#pragma GCC diagnostic ignored "-Woverloaded-virtual"
+
 /* A command that requires a Nix store. */
 struct StoreCommand : virtual Command
 {
@@ -97,10 +100,10 @@ struct SourceExprCommand : virtual Args, MixFlakeOptions
 
     SourceExprCommand();
 
-    std::vector<std::shared_ptr<Installable>> parseInstallables(
+    Installables parseInstallables(
         ref<Store> store, std::vector<std::string> ss);
 
-    std::shared_ptr<Installable> parseInstallable(
+    ref<Installable> parseInstallable(
         ref<Store> store, const std::string & installable);
 
     virtual Strings getDefaultFlakeAttrPaths();
@@ -115,36 +118,43 @@ struct MixReadOnlyOption : virtual Args
     MixReadOnlyOption();
 };
 
-/* A command that operates on a list of "installables", which can be
-   store paths, attribute paths, Nix expressions, etc. */
-struct InstallablesCommand : virtual Args, SourceExprCommand
+/* Like InstallablesCommand but the installables are not loaded */
+struct RawInstallablesCommand : virtual Args, SourceExprCommand
 {
-    std::vector<std::shared_ptr<Installable>> installables;
+    RawInstallablesCommand();
 
-    InstallablesCommand();
+    virtual void run(ref<Store> store, std::vector<std::string> && rawInstallables) = 0;
 
-    void prepare() override;
-    Installables load();
+    void run(ref<Store> store) override;
 
-    virtual bool useDefaultInstallables() { return true; }
+    // FIXME make const after CmdRepl's override is fixed up
+    virtual void applyDefaultInstallables(std::vector<std::string> & rawInstallables);
 
     bool readFromStdIn = false;
 
     std::vector<std::string> getFlakesForCompletion() override;
 
-protected:
+private:
 
-    std::vector<std::string> _installables;
+    std::vector<std::string> rawInstallables;
+};
+/* A command that operates on a list of "installables", which can be
+   store paths, attribute paths, Nix expressions, etc. */
+struct InstallablesCommand : RawInstallablesCommand
+{
+    virtual void run(ref<Store> store, Installables && installables) = 0;
+
+    void run(ref<Store> store, std::vector<std::string> && rawInstallables) override;
 };
 
 /* A command that operates on exactly one "installable" */
 struct InstallableCommand : virtual Args, SourceExprCommand
 {
-    std::shared_ptr<Installable> installable;
-
     InstallableCommand();
 
-    void prepare() override;
+    virtual void run(ref<Store> store, ref<Installable> installable) = 0;
+
+    void run(ref<Store> store) override;
 
     std::vector<std::string> getFlakesForCompletion() override
     {
@@ -179,22 +189,18 @@ public:
 
     BuiltPathsCommand(bool recursive = false);
 
-    using StoreCommand::run;
-
     virtual void run(ref<Store> store, BuiltPaths && paths) = 0;
 
-    void run(ref<Store> store) override;
+    void run(ref<Store> store, Installables && installables) override;
 
-    bool useDefaultInstallables() override { return !all; }
+    void applyDefaultInstallables(std::vector<std::string> & rawInstallables) override;
 };
 
 struct StorePathsCommand : public BuiltPathsCommand
 {
     StorePathsCommand(bool recursive = false);
 
-    using BuiltPathsCommand::run;
-
-    virtual void run(ref<Store> store, std::vector<StorePath> && storePaths) = 0;
+    virtual void run(ref<Store> store, StorePaths && storePaths) = 0;
 
     void run(ref<Store> store, BuiltPaths && paths) override;
 };
@@ -202,11 +208,9 @@ struct StorePathsCommand : public BuiltPathsCommand
 /* A command that operates on exactly one store path. */
 struct StorePathCommand : public StorePathsCommand
 {
-    using StorePathsCommand::run;
-
     virtual void run(ref<Store> store, const StorePath & storePath) = 0;
 
-    void run(ref<Store> store, std::vector<StorePath> && storePaths) override;
+    void run(ref<Store> store, StorePaths && storePaths) override;
 };
 
 /* A helper class for registering commands globally. */
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 5ecf6293f..5cbf26b88 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -422,10 +422,10 @@ ref<eval_cache::EvalCache> openEvalCache(
         });
 }
 
-std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
+Installables SourceExprCommand::parseInstallables(
     ref<Store> store, std::vector<std::string> ss)
 {
-    std::vector<std::shared_ptr<Installable>> result;
+    Installables result;
 
     if (file || expr) {
         if (file && expr)
@@ -451,7 +451,7 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
         for (auto & s : ss) {
             auto [prefix, extendedOutputsSpec] = ExtendedOutputsSpec::parse(s);
             result.push_back(
-                std::make_shared<InstallableAttrPath>(
+                make_ref<InstallableAttrPath>(
                     InstallableAttrPath::parse(
                         state, *this, vFile, prefix, extendedOutputsSpec)));
         }
@@ -468,7 +468,7 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
 
             if (prefix.find('/') != std::string::npos) {
                 try {
-                    result.push_back(std::make_shared<InstallableDerivedPath>(
+                    result.push_back(make_ref<InstallableDerivedPath>(
                         InstallableDerivedPath::parse(store, prefix, extendedOutputsSpec)));
                     continue;
                 } catch (BadStorePath &) {
@@ -480,7 +480,7 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
 
             try {
                 auto [flakeRef, fragment] = parseFlakeRefWithFragment(std::string { prefix }, absPath("."));
-                result.push_back(std::make_shared<InstallableFlake>(
+                result.push_back(make_ref<InstallableFlake>(
                         this,
                         getEvalState(),
                         std::move(flakeRef),
@@ -501,7 +501,7 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
     return result;
 }
 
-std::shared_ptr<Installable> SourceExprCommand::parseInstallable(
+ref<Installable> SourceExprCommand::parseInstallable(
     ref<Store> store, const std::string & installable)
 {
     auto installables = parseInstallables(store, {installable});
@@ -513,7 +513,7 @@ std::vector<BuiltPathWithResult> Installable::build(
     ref<Store> evalStore,
     ref<Store> store,
     Realise mode,
-    const std::vector<std::shared_ptr<Installable>> & installables,
+    const Installables & installables,
     BuildMode bMode)
 {
     std::vector<BuiltPathWithResult> res;
@@ -522,11 +522,11 @@ std::vector<BuiltPathWithResult> Installable::build(
     return res;
 }
 
-std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> Installable::build2(
+std::vector<std::pair<ref<Installable>, BuiltPathWithResult>> Installable::build2(
     ref<Store> evalStore,
     ref<Store> store,
     Realise mode,
-    const std::vector<std::shared_ptr<Installable>> & installables,
+    const Installables & installables,
     BuildMode bMode)
 {
     if (mode == Realise::Nothing)
@@ -535,7 +535,7 @@ std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> Instal
     struct Aux
     {
         ExtraPathInfo info;
-        std::shared_ptr<Installable> installable;
+        ref<Installable> installable;
     };
 
     std::vector<DerivedPath> pathsToBuild;
@@ -548,7 +548,7 @@ std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> Instal
         }
     }
 
-    std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> res;
+    std::vector<std::pair<ref<Installable>, BuiltPathWithResult>> res;
 
     switch (mode) {
 
@@ -620,7 +620,7 @@ BuiltPaths Installable::toBuiltPaths(
     ref<Store> store,
     Realise mode,
     OperateOn operateOn,
-    const std::vector<std::shared_ptr<Installable>> & installables)
+    const Installables & installables)
 {
     if (operateOn == OperateOn::Output) {
         BuiltPaths res;
@@ -642,7 +642,7 @@ StorePathSet Installable::toStorePaths(
     ref<Store> evalStore,
     ref<Store> store,
     Realise mode, OperateOn operateOn,
-    const std::vector<std::shared_ptr<Installable>> & installables)
+    const Installables & installables)
 {
     StorePathSet outPaths;
     for (auto & path : toBuiltPaths(evalStore, store, mode, operateOn, installables)) {
@@ -656,7 +656,7 @@ StorePath Installable::toStorePath(
     ref<Store> evalStore,
     ref<Store> store,
     Realise mode, OperateOn operateOn,
-    std::shared_ptr<Installable> installable)
+    ref<Installable> installable)
 {
     auto paths = toStorePaths(evalStore, store, mode, operateOn, {installable});
 
@@ -668,7 +668,7 @@ StorePath Installable::toStorePath(
 
 StorePathSet Installable::toDerivations(
     ref<Store> store,
-    const std::vector<std::shared_ptr<Installable>> & installables,
+    const Installables & installables,
     bool useDeriver)
 {
     StorePathSet drvPaths;
@@ -692,9 +692,8 @@ StorePathSet Installable::toDerivations(
     return drvPaths;
 }
 
-InstallablesCommand::InstallablesCommand()
+RawInstallablesCommand::RawInstallablesCommand()
 {
-
     addFlag({
         .longName = "stdin",
         .description = "Read installables from the standard input.",
@@ -703,40 +702,45 @@ InstallablesCommand::InstallablesCommand()
 
     expectArgs({
         .label = "installables",
-        .handler = {&_installables},
+        .handler = {&rawInstallables},
         .completer = {[&](size_t, std::string_view prefix) {
             completeInstallable(prefix);
         }}
     });
 }
 
-void InstallablesCommand::prepare()
+void RawInstallablesCommand::applyDefaultInstallables(std::vector<std::string> & rawInstallables)
 {
-    installables = load();
-}
-
-Installables InstallablesCommand::load()
-{
-    if (_installables.empty() && useDefaultInstallables() && !readFromStdIn)
+    if (rawInstallables.empty()) {
         // FIXME: commands like "nix profile install" should not have a
         // default, probably.
-        _installables.push_back(".");
+        rawInstallables.push_back(".");
+    }
+}
 
+void RawInstallablesCommand::run(ref<Store> store)
+{
     if (readFromStdIn && !isatty(STDIN_FILENO)) {
         std::string word;
         while (std::cin >> word) {
-            _installables.emplace_back(std::move(word));
+            rawInstallables.emplace_back(std::move(word));
         }
     }
 
-    return parseInstallables(getStore(), _installables);
+    applyDefaultInstallables(rawInstallables);
+    run(store, std::move(rawInstallables));
 }
 
-std::vector<std::string> InstallablesCommand::getFlakesForCompletion()
+std::vector<std::string> RawInstallablesCommand::getFlakesForCompletion()
 {
-    if (_installables.empty() && useDefaultInstallables())
-        return {"."};
-    return _installables;
+    applyDefaultInstallables(rawInstallables);
+    return rawInstallables;
+}
+
+void InstallablesCommand::run(ref<Store> store, std::vector<std::string> && rawInstallables)
+{
+    auto installables = parseInstallables(store, rawInstallables);
+    run(store, std::move(installables));
 }
 
 InstallableCommand::InstallableCommand()
@@ -752,9 +756,16 @@ InstallableCommand::InstallableCommand()
     });
 }
 
-void InstallableCommand::prepare()
+void InstallableCommand::run(ref<Store> store)
 {
-    installable = parseInstallable(getStore(), _installable);
+    auto installable = parseInstallable(store, _installable);
+    run(store, std::move(installable));
+}
+
+void BuiltPathsCommand::applyDefaultInstallables(std::vector<std::string> & rawInstallables)
+{
+    if (rawInstallables.empty() && !all)
+        rawInstallables.push_back(".");
 }
 
 }
diff --git a/src/libcmd/installables.hh b/src/libcmd/installables.hh
index be77fdc81..6c2922d89 100644
--- a/src/libcmd/installables.hh
+++ b/src/libcmd/installables.hh
@@ -79,6 +79,9 @@ struct BuiltPathWithResult
 
 typedef std::vector<DerivedPathWithInfo> DerivedPathsWithInfo;
 
+struct Installable;
+typedef std::vector<ref<Installable>> Installables;
+
 struct Installable
 {
     virtual ~Installable() { }
@@ -122,14 +125,14 @@ struct Installable
         ref<Store> evalStore,
         ref<Store> store,
         Realise mode,
-        const std::vector<std::shared_ptr<Installable>> & installables,
+        const Installables & installables,
         BuildMode bMode = bmNormal);
 
-    static std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> build2(
+    static std::vector<std::pair<ref<Installable>, BuiltPathWithResult>> build2(
         ref<Store> evalStore,
         ref<Store> store,
         Realise mode,
-        const std::vector<std::shared_ptr<Installable>> & installables,
+        const Installables & installables,
         BuildMode bMode = bmNormal);
 
     static std::set<StorePath> toStorePaths(
@@ -137,18 +140,18 @@ struct Installable
         ref<Store> store,
         Realise mode,
         OperateOn operateOn,
-        const std::vector<std::shared_ptr<Installable>> & installables);
+        const Installables & installables);
 
     static StorePath toStorePath(
         ref<Store> evalStore,
         ref<Store> store,
         Realise mode,
         OperateOn operateOn,
-        std::shared_ptr<Installable> installable);
+        ref<Installable> installable);
 
     static std::set<StorePath> toDerivations(
         ref<Store> store,
-        const std::vector<std::shared_ptr<Installable>> & installables,
+        const Installables & installables,
         bool useDeriver = false);
 
     static BuiltPaths toBuiltPaths(
@@ -156,9 +159,7 @@ struct Installable
         ref<Store> store,
         Realise mode,
         OperateOn operateOn,
-        const std::vector<std::shared_ptr<Installable>> & installables);
+        const Installables & installables);
 };
 
-typedef std::vector<std::shared_ptr<Installable>> Installables;
-
 }
diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index 84866f12b..7211ee307 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -198,7 +198,6 @@ struct Command : virtual public Args
 
     virtual ~Command() { }
 
-    virtual void prepare() { };
     virtual void run() = 0;
 
     typedef int Category;
diff --git a/src/nix/app.cc b/src/nix/app.cc
index 5cd65136f..bfd75e278 100644
--- a/src/nix/app.cc
+++ b/src/nix/app.cc
@@ -119,11 +119,11 @@ App UnresolvedApp::resolve(ref<Store> evalStore, ref<Store> store)
 {
     auto res = unresolved;
 
-    std::vector<std::shared_ptr<Installable>> installableContext;
+    Installables installableContext;
 
     for (auto & ctxElt : unresolved.context)
         installableContext.push_back(
-            std::make_shared<InstallableDerivedPath>(store, DerivedPath { ctxElt }));
+            make_ref<InstallableDerivedPath>(store, DerivedPath { ctxElt }));
 
     auto builtContext = Installable::build(evalStore, store, Realise::Outputs, installableContext);
     res.program = resolveString(*store, unresolved.program, builtContext);
diff --git a/src/nix/build.cc b/src/nix/build.cc
index f4f2ec81d..f8593135e 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -89,7 +89,7 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixJSON, MixProfile
           ;
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, Installables && installables) override
     {
         if (dryRun) {
             std::vector<DerivedPath> pathsToBuild;
diff --git a/src/nix/bundle.cc b/src/nix/bundle.cc
index dcf9a6f2d..973bbd423 100644
--- a/src/nix/bundle.cc
+++ b/src/nix/bundle.cc
@@ -70,7 +70,7 @@ struct CmdBundle : InstallableCommand
         return res;
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         auto evalState = getEvalState();
 
diff --git a/src/nix/copy.cc b/src/nix/copy.cc
index 8730a9a5c..151d28277 100644
--- a/src/nix/copy.cc
+++ b/src/nix/copy.cc
@@ -10,8 +10,6 @@ struct CmdCopy : virtual CopyCommand, virtual BuiltPathsCommand
 
     SubstituteFlag substitute = NoSubstitute;
 
-    using BuiltPathsCommand::run;
-
     CmdCopy()
         : BuiltPathsCommand(true)
     {
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 0ee533e85..f06ade008 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -374,7 +374,7 @@ struct Common : InstallableCommand, MixProfile
         return res;
     }
 
-    StorePath getShellOutPath(ref<Store> store)
+    StorePath getShellOutPath(ref<Store> store, ref<Installable> installable)
     {
         auto path = installable->getStorePath();
         if (path && hasSuffix(path->to_string(), "-env"))
@@ -392,9 +392,10 @@ struct Common : InstallableCommand, MixProfile
         }
     }
 
-    std::pair<BuildEnvironment, std::string> getBuildEnvironment(ref<Store> store)
+    std::pair<BuildEnvironment, std::string>
+    getBuildEnvironment(ref<Store> store, ref<Installable> installable)
     {
-        auto shellOutPath = getShellOutPath(store);
+        auto shellOutPath = getShellOutPath(store, installable);
 
         auto strPath = store->printStorePath(shellOutPath);
 
@@ -480,9 +481,9 @@ struct CmdDevelop : Common, MixEnvironment
           ;
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
-        auto [buildEnvironment, gcroot] = getBuildEnvironment(store);
+        auto [buildEnvironment, gcroot] = getBuildEnvironment(store, installable);
 
         auto [rcFileFd, rcFilePath] = createTempFile("nix-shell");
 
@@ -537,7 +538,7 @@ struct CmdDevelop : Common, MixEnvironment
             nixpkgsLockFlags.inputOverrides = {};
             nixpkgsLockFlags.inputUpdates = {};
 
-            auto bashInstallable = std::make_shared<InstallableFlake>(
+            auto bashInstallable = make_ref<InstallableFlake>(
                 this,
                 state,
                 installable->nixpkgsFlakeRef(),
@@ -573,7 +574,7 @@ struct CmdDevelop : Common, MixEnvironment
         // Need to chdir since phases assume in flake directory
         if (phase) {
             // chdir if installable is a flake of type git+file or path
-            auto installableFlake = std::dynamic_pointer_cast<InstallableFlake>(installable);
+            auto installableFlake = installable.dynamic_pointer_cast<InstallableFlake>();
             if (installableFlake) {
                 auto sourcePath = installableFlake->getLockedFlake()->flake.resolvedRef.input.getSourcePath();
                 if (sourcePath) {
@@ -604,9 +605,9 @@ struct CmdPrintDevEnv : Common, MixJSON
 
     Category category() override { return catUtility; }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
-        auto buildEnvironment = getBuildEnvironment(store).first;
+        auto buildEnvironment = getBuildEnvironment(store, installable).first;
 
         stopProgressBar();
 
diff --git a/src/nix/edit.cc b/src/nix/edit.cc
index dfe75fbdf..c46c1c23c 100644
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -25,7 +25,7 @@ struct CmdEdit : InstallableCommand
 
     Category category() override { return catSecondary; }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         auto state = getEvalState();
 
diff --git a/src/nix/eval.cc b/src/nix/eval.cc
index 209fd3ed2..6c2b60427 100644
--- a/src/nix/eval.cc
+++ b/src/nix/eval.cc
@@ -54,7 +54,7 @@ struct CmdEval : MixJSON, InstallableCommand, MixReadOnlyOption
 
     Category category() override { return catSecondary; }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         if (raw && json)
             throw UsageError("--raw and --json are mutually exclusive");
diff --git a/src/nix/flake.cc b/src/nix/flake.cc
index 3fe093fc7..0a6616396 100644
--- a/src/nix/flake.cc
+++ b/src/nix/flake.cc
@@ -1329,7 +1329,6 @@ struct CmdFlake : NixMultiCommand
         if (!command)
             throw UsageError("'nix flake' requires a sub-command.");
         settings.requireExperimentalFeature(Xp::Flakes);
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/hash.cc b/src/nix/hash.cc
index 60d9593a7..6d95c0455 100644
--- a/src/nix/hash.cc
+++ b/src/nix/hash.cc
@@ -151,7 +151,6 @@ struct CmdHash : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix hash' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/log.cc b/src/nix/log.cc
index 0c9f778f0..aaf829764 100644
--- a/src/nix/log.cc
+++ b/src/nix/log.cc
@@ -23,7 +23,7 @@ struct CmdLog : InstallableCommand
 
     Category category() override { return catSecondary; }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         settings.readOnlyMode = true;
 
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 53bf649d4..7b715f281 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -394,7 +394,6 @@ void mainWrapped(int argc, char * * argv)
     if (args.command->second->forceImpureByDefault() && !evalSettings.pureEval.overridden) {
         evalSettings.pureEval = false;
     }
-    args.command->second->prepare();
     args.command->second->run();
 }
 
diff --git a/src/nix/make-content-addressed.cc b/src/nix/make-content-addressed.cc
index 6693c55ac..d9c988a9f 100644
--- a/src/nix/make-content-addressed.cc
+++ b/src/nix/make-content-addressed.cc
@@ -28,7 +28,6 @@ struct CmdMakeContentAddressed : virtual CopyCommand, virtual StorePathsCommand,
           ;
     }
 
-    using StorePathsCommand::run;
     void run(ref<Store> srcStore, StorePaths && storePaths) override
     {
         auto dstStore = dstUri.empty() ? openStore() : openStore(dstUri);
diff --git a/src/nix/nar.cc b/src/nix/nar.cc
index dbb043d9b..9815410cf 100644
--- a/src/nix/nar.cc
+++ b/src/nix/nar.cc
@@ -25,7 +25,6 @@ struct CmdNar : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix nar' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/profile.cc b/src/nix/profile.cc
index eef33b3d9..d72dd1a13 100644
--- a/src/nix/profile.cc
+++ b/src/nix/profile.cc
@@ -256,11 +256,11 @@ struct ProfileManifest
 
 static std::map<Installable *, std::pair<BuiltPaths, ExtraPathInfo>>
 builtPathsPerInstallable(
-    const std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> & builtPaths)
+    const std::vector<std::pair<ref<Installable>, BuiltPathWithResult>> & builtPaths)
 {
     std::map<Installable *, std::pair<BuiltPaths, ExtraPathInfo>> res;
     for (auto & [installable, builtPath] : builtPaths) {
-        auto & r = res[installable.get()];
+        auto & r = res[&*installable];
         /* Note that there could be conflicting info
            (e.g. meta.priority fields) if the installable returned
            multiple derivations. So pick one arbitrarily. FIXME:
@@ -296,7 +296,7 @@ struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
           ;
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, Installables && installables) override
     {
         ProfileManifest manifest(*getEvalState(), *profile);
 
@@ -307,7 +307,7 @@ struct CmdProfileInstall : InstallablesCommand, MixDefaultProfile
         for (auto & installable : installables) {
             ProfileElement element;
 
-            auto & [res, info] = builtPaths[installable.get()];
+            auto & [res, info] = builtPaths[&*installable];
 
             if (info.originalRef && info.resolvedRef && info.attrPath && info.extendedOutputsSpec) {
                 element.source = ProfileElementSource {
@@ -513,7 +513,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
 
         auto matchers = getMatchers(store);
 
-        std::vector<std::shared_ptr<Installable>> installables;
+        Installables installables;
         std::vector<size_t> indices;
 
         auto upgradedCount = 0;
@@ -529,7 +529,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
                 Activity act(*logger, lvlChatty, actUnknown,
                     fmt("checking '%s' for updates", element.source->attrPath));
 
-                auto installable = std::make_shared<InstallableFlake>(
+                auto installable = make_ref<InstallableFlake>(
                     this,
                     getEvalState(),
                     FlakeRef(element.source->originalRef),
@@ -582,7 +582,7 @@ struct CmdProfileUpgrade : virtual SourceExprCommand, MixDefaultProfile, MixProf
         for (size_t i = 0; i < installables.size(); ++i) {
             auto & installable = installables.at(i);
             auto & element = manifest.elements[indices.at(i)];
-            element.updateStorePaths(getEvalStore(), store, builtPaths[installable.get()].first);
+            element.updateStorePaths(getEvalStore(), store, builtPaths[&*installable].first);
         }
 
         updateProfile(manifest.build(store));
@@ -798,7 +798,6 @@ struct CmdProfile : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix profile' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/realisation.cc b/src/nix/realisation.cc
index 0d3466515..13db80282 100644
--- a/src/nix/realisation.cc
+++ b/src/nix/realisation.cc
@@ -21,7 +21,6 @@ struct CmdRealisation : virtual NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix realisation' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/registry.cc b/src/nix/registry.cc
index b5bdfba95..1f4f820ac 100644
--- a/src/nix/registry.cc
+++ b/src/nix/registry.cc
@@ -227,7 +227,6 @@ struct CmdRegistry : virtual NixMultiCommand
         settings.requireExperimentalFeature(Xp::Flakes);
         if (!command)
             throw UsageError("'nix registry' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 679bdea77..51d3074b4 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -5,26 +5,12 @@
 
 namespace nix {
 
-struct CmdRepl : InstallablesCommand
+struct CmdRepl : RawInstallablesCommand
 {
     CmdRepl() {
         evalSettings.pureEval = false;
     }
 
-    void prepare() override
-    {
-        if (!settings.isExperimentalFeatureEnabled(Xp::ReplFlake) && !(file) && this->_installables.size() >= 1) {
-            warn("future versions of Nix will require using `--file` to load a file");
-            if (this->_installables.size() > 1)
-                warn("more than one input file is not currently supported");
-            auto filePath = this->_installables[0].data();
-            file = std::optional(filePath);
-            _installables.front() = _installables.back();
-            _installables.pop_back();
-        }
-        installables = InstallablesCommand::load();
-    }
-
     std::vector<std::string> files;
 
     Strings getDefaultFlakeAttrPaths() override
@@ -32,11 +18,6 @@ struct CmdRepl : InstallablesCommand
         return {""};
     }
 
-    bool useDefaultInstallables() override
-    {
-        return file.has_value() or expr.has_value();
-    }
-
     bool forceImpureByDefault() override
     {
         return true;
@@ -54,11 +35,27 @@ struct CmdRepl : InstallablesCommand
           ;
     }
 
-    void run(ref<Store> store) override
+    void applyDefaultInstallables(std::vector<std::string> & rawInstallables) override
+    {
+        if (!settings.isExperimentalFeatureEnabled(Xp::ReplFlake) && !(file) && rawInstallables.size() >= 1) {
+            warn("future versions of Nix will require using `--file` to load a file");
+            if (rawInstallables.size() > 1)
+                warn("more than one input file is not currently supported");
+            auto filePath = rawInstallables[0].data();
+            file = std::optional(filePath);
+            rawInstallables.front() = rawInstallables.back();
+            rawInstallables.pop_back();
+        }
+        if (rawInstallables.empty() && (file.has_value() || expr.has_value())) {
+            rawInstallables.push_back(".");
+        }
+    }
+
+    void run(ref<Store> store, std::vector<std::string> && rawInstallables) override
     {
         auto state = getEvalState();
         auto getValues = [&]()->AbstractNixRepl::AnnotatedValues{
-            auto installables = load();
+            auto installables = parseInstallables(store, rawInstallables);
             AbstractNixRepl::AnnotatedValues values;
             for (auto & installable: installables){
                 auto what = installable->what();
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 6fca68047..56605d9d5 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -97,7 +97,7 @@ struct CmdShell : InstallablesCommand, MixEnvironment
           ;
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, Installables && installables) override
     {
         auto outPaths = Installable::toStorePaths(getEvalStore(), store, Realise::Outputs, OperateOn::Output, installables);
 
@@ -183,7 +183,7 @@ struct CmdRun : InstallableCommand
         return res;
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         auto state = getEvalState();
 
diff --git a/src/nix/search.cc b/src/nix/search.cc
index 2e38f7e4b..994ec44c2 100644
--- a/src/nix/search.cc
+++ b/src/nix/search.cc
@@ -61,7 +61,7 @@ struct CmdSearch : InstallableCommand, MixJSON
         };
     }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, ref<Installable> installable) override
     {
         settings.readOnlyMode = true;
         evalSettings.enableImportFromDerivation.setDefault(false);
diff --git a/src/nix/show-derivation.cc b/src/nix/show-derivation.cc
index 520e8b1ce..4a406ae08 100644
--- a/src/nix/show-derivation.cc
+++ b/src/nix/show-derivation.cc
@@ -39,7 +39,7 @@ struct CmdShowDerivation : InstallablesCommand
 
     Category category() override { return catUtility; }
 
-    void run(ref<Store> store) override
+    void run(ref<Store> store, Installables && installables) override
     {
         auto drvPaths = Installable::toDerivations(store, installables, true);
 
diff --git a/src/nix/sigs.cc b/src/nix/sigs.cc
index 1431652e0..45cd2e1a6 100644
--- a/src/nix/sigs.cc
+++ b/src/nix/sigs.cc
@@ -219,7 +219,6 @@ struct CmdKey : NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix key' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };
diff --git a/src/nix/store-copy-log.cc b/src/nix/store-copy-log.cc
index d5fab5f2f..1dda8c0b8 100644
--- a/src/nix/store-copy-log.cc
+++ b/src/nix/store-copy-log.cc
@@ -26,7 +26,7 @@ struct CmdCopyLog : virtual CopyCommand, virtual InstallablesCommand
 
     Category category() override { return catUtility; }
 
-    void run(ref<Store> srcStore) override
+    void run(ref<Store> srcStore, Installables && installables) override
     {
         auto & srcLogStore = require<LogStore>(*srcStore);
 
diff --git a/src/nix/store-delete.cc b/src/nix/store-delete.cc
index ca43f1530..6719227df 100644
--- a/src/nix/store-delete.cc
+++ b/src/nix/store-delete.cc
@@ -32,7 +32,7 @@ struct CmdStoreDelete : StorePathsCommand
           ;
     }
 
-    void run(ref<Store> store, std::vector<StorePath> && storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         auto & gcStore = require<GcStore>(*store);
 
diff --git a/src/nix/store-repair.cc b/src/nix/store-repair.cc
index 8fcb3639a..895e39685 100644
--- a/src/nix/store-repair.cc
+++ b/src/nix/store-repair.cc
@@ -17,7 +17,7 @@ struct CmdStoreRepair : StorePathsCommand
           ;
     }
 
-    void run(ref<Store> store, std::vector<StorePath> && storePaths) override
+    void run(ref<Store> store, StorePaths && storePaths) override
     {
         for (auto & path : storePaths)
             store->repairPath(path);
diff --git a/src/nix/store.cc b/src/nix/store.cc
index 44e53c7c7..2879e03b3 100644
--- a/src/nix/store.cc
+++ b/src/nix/store.cc
@@ -18,7 +18,6 @@ struct CmdStore : virtual NixMultiCommand
     {
         if (!command)
             throw UsageError("'nix store' requires a sub-command.");
-        command->second->prepare();
         command->second->run();
     }
 };