diff --git a/src/nix/build.cc b/src/nix/build.cc
index 474337208..0f7e0e123 100644
--- a/src/nix/build.cc
+++ b/src/nix/build.cc
@@ -53,7 +53,7 @@ struct CmdBuild : InstallablesCommand, MixDryRun, MixProfile
 
     void run(ref<Store> store) override
     {
-        auto buildables = build(store, dryRun ? DryRun : Build, installables);
+        auto buildables = build(store, dryRun ? Realise::Nothing : Realise::Outputs, installables);
 
         if (dryRun) return;
 
diff --git a/src/nix/command.cc b/src/nix/command.cc
index dbf5e0988..a4faccb6d 100644
--- a/src/nix/command.cc
+++ b/src/nix/command.cc
@@ -80,7 +80,7 @@ void StorePathsCommand::run(ref<Store> store)
 
 void StorePathCommand::run(ref<Store> store)
 {
-    auto storePaths = toStorePaths(store, NoBuild, installables);
+    auto storePaths = toStorePaths(store, Realise::Nothing, installables);
 
     if (storePaths.size() != 1)
         throw UsageError("this command requires exactly one store path");
diff --git a/src/nix/command.hh b/src/nix/command.hh
index a8779b0e6..5fa8f9333 100644
--- a/src/nix/command.hh
+++ b/src/nix/command.hh
@@ -70,7 +70,16 @@ struct SourceExprCommand : virtual Args, MixFlakeOptions
     void completeInstallable(std::string_view prefix);
 };
 
-enum RealiseMode { Build, NoBuild, DryRun };
+enum class Realise {
+    /* Build the derivation. Postcondition: the
+       derivation outputs exist. */
+    Outputs,
+    /* Don't build the derivation. Postcondition: the store derivation
+       exists. */
+    Derivation,
+    /* Evaluate in dry-run mode. Postcondition: nothing. */
+    Nothing
+};
 
 /* A command that operates on a list of "installables", which can be
    store paths, attribute paths, Nix expressions, etc. */
@@ -120,7 +129,7 @@ private:
 
 protected:
 
-    RealiseMode realiseMode = NoBuild;
+    Realise realiseMode = Realise::Derivation;
 
 public:
 
@@ -164,13 +173,13 @@ static RegisterCommand registerCommand(const std::string & name)
     return RegisterCommand(name, [](){ return make_ref<T>(); });
 }
 
-Buildables build(ref<Store> store, RealiseMode mode,
+Buildables build(ref<Store> store, Realise mode,
     std::vector<std::shared_ptr<Installable>> installables);
 
-std::set<StorePath> toStorePaths(ref<Store> store, RealiseMode mode,
+std::set<StorePath> toStorePaths(ref<Store> store, Realise mode,
     std::vector<std::shared_ptr<Installable>> installables);
 
-StorePath toStorePath(ref<Store> store, RealiseMode mode,
+StorePath toStorePath(ref<Store> store, Realise mode,
     std::shared_ptr<Installable> installable);
 
 std::set<StorePath> toDerivations(ref<Store> store,
diff --git a/src/nix/copy.cc b/src/nix/copy.cc
index 815e653b0..5281ff5ee 100644
--- a/src/nix/copy.cc
+++ b/src/nix/copy.cc
@@ -46,7 +46,7 @@ struct CmdCopy : StorePathsCommand
             .handler = {&substitute, Substitute},
         });
 
-        realiseMode = Build;
+        realiseMode = Realise::Outputs;
     }
 
     std::string description() override
diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index 171eeeb3c..bf4890e95 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -321,7 +321,7 @@ struct CmdDevelop : Common, MixEnvironment
                 Strings{"legacyPackages." + settings.thisSystem.get() + "."},
                 lockFlags);
 
-            shell = state->store->printStorePath(toStorePath(state->store, Build, bashInstallable)) + "/bin/bash";
+            shell = state->store->printStorePath(toStorePath(state->store, Realise::Outputs, bashInstallable)) + "/bin/bash";
         } catch (Error &) {
             ignoreException();
         }
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index 415358970..d464efc35 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -635,10 +635,10 @@ std::shared_ptr<Installable> SourceExprCommand::parseInstallable(
     return installables.front();
 }
 
-Buildables build(ref<Store> store, RealiseMode mode,
+Buildables build(ref<Store> store, Realise mode,
     std::vector<std::shared_ptr<Installable>> installables)
 {
-    if (mode != Build)
+    if (mode == Realise::Nothing)
         settings.readOnlyMode = true;
 
     Buildables buildables;
@@ -659,15 +659,15 @@ Buildables build(ref<Store> store, RealiseMode mode,
         }
     }
 
-    if (mode == DryRun)
+    if (mode == Realise::Nothing)
         printMissing(store, pathsToBuild, lvlError);
-    else if (mode == Build)
+    else if (mode == Realise::Outputs)
         store->buildPaths(pathsToBuild);
 
     return buildables;
 }
 
-StorePathSet toStorePaths(ref<Store> store, RealiseMode mode,
+StorePathSet toStorePaths(ref<Store> store, Realise mode,
     std::vector<std::shared_ptr<Installable>> installables)
 {
     StorePathSet outPaths;
@@ -679,7 +679,7 @@ StorePathSet toStorePaths(ref<Store> store, RealiseMode mode,
     return outPaths;
 }
 
-StorePath toStorePath(ref<Store> store, RealiseMode mode,
+StorePath toStorePath(ref<Store> store, Realise mode,
     std::shared_ptr<Installable> installable)
 {
     auto paths = toStorePaths(store, mode, {installable});
diff --git a/src/nix/make-content-addressable.cc b/src/nix/make-content-addressable.cc
index fb36fc410..b2ded35dd 100644
--- a/src/nix/make-content-addressable.cc
+++ b/src/nix/make-content-addressable.cc
@@ -10,7 +10,7 @@ struct CmdMakeContentAddressable : StorePathsCommand, MixJSON
 {
     CmdMakeContentAddressable()
     {
-        realiseMode = Build;
+        realiseMode = Realise::Outputs;
     }
 
     std::string description() override
diff --git a/src/nix/run.cc b/src/nix/run.cc
index 59a6c7252..a27538085 100644
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -104,7 +104,7 @@ struct CmdShell : InstallablesCommand, RunCommon, MixEnvironment
 
     void run(ref<Store> store) override
     {
-        auto outPaths = toStorePaths(store, Build, installables);
+        auto outPaths = toStorePaths(store, Realise::Outputs, installables);
 
         auto accessor = store->getFSAccessor();
 
diff --git a/src/nix/why-depends.cc b/src/nix/why-depends.cc
index a208e0081..c39a0435d 100644
--- a/src/nix/why-depends.cc
+++ b/src/nix/why-depends.cc
@@ -73,9 +73,9 @@ struct CmdWhyDepends : SourceExprCommand
     void run(ref<Store> store) override
     {
         auto package = parseInstallable(store, _package);
-        auto packagePath = toStorePath(store, Build, package);
+        auto packagePath = toStorePath(store, Realise::Outputs, package);
         auto dependency = parseInstallable(store, _dependency);
-        auto dependencyPath = toStorePath(store, NoBuild, dependency);
+        auto dependencyPath = toStorePath(store, Realise::Derivation, dependency);
         auto dependencyPathHash = dependencyPath.hashPart();
 
         StorePathSet closure;