diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index 93f20a8c3..4add710ed 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -56,14 +56,6 @@ void StoreCommand::run()
 
 EvalCommand::EvalCommand()
 {
-    // FIXME: move to MixEvalArgs?
-    addFlag({
-        .longName = "eval-store",
-        .description = "The Nix store to use for evaluations.",
-        .labels = {"store-url"},
-        //.category = ...,
-        .handler = {&evalStoreUrl},
-    });
 }
 
 EvalCommand::~EvalCommand()
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 3aba8f25f..659b13559 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -54,8 +54,6 @@ struct EvalCommand : virtual StoreCommand, MixEvalArgs
     ref<EvalState> getEvalState();
 
 private:
-    std::optional<std::string> evalStoreUrl;
-
     std::shared_ptr<Store> evalStore;
 
     std::shared_ptr<EvalState> evalState;
diff --git a/src/libexpr/common-eval-args.cc b/src/libexpr/common-eval-args.cc
index aa14bf79b..fb0932c00 100644
--- a/src/libexpr/common-eval-args.cc
+++ b/src/libexpr/common-eval-args.cc
@@ -61,6 +61,14 @@ MixEvalArgs::MixEvalArgs()
             fetchers::overrideRegistry(from.input, to.input, extraAttrs);
         }}
     });
+
+    addFlag({
+        .longName = "eval-store",
+        .description = "The Nix store to use for evaluations.",
+        .category = category,
+        .labels = {"store-url"},
+        .handler = {&evalStoreUrl},
+    });
 }
 
 Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
diff --git a/src/libexpr/common-eval-args.hh b/src/libexpr/common-eval-args.hh
index be7fda783..0e113fff1 100644
--- a/src/libexpr/common-eval-args.hh
+++ b/src/libexpr/common-eval-args.hh
@@ -16,8 +16,9 @@ struct MixEvalArgs : virtual Args
 
     Strings searchPath;
 
-private:
+    std::optional<std::string> evalStoreUrl;
 
+private:
     std::map<std::string, std::string> autoArgs;
 };
 
diff --git a/src/nix-build/nix-build.cc b/src/nix-build/nix-build.cc
index 29be46cf5..4305c0ac1 100755
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -250,8 +250,9 @@ static void main_nix_build(int argc, char * * argv)
         throw UsageError("'-p' and '-E' are mutually exclusive");
 
     auto store = openStore();
+    auto evalStore = myArgs.evalStoreUrl ? openStore(*myArgs.evalStoreUrl) : store;
 
-    auto state = std::make_unique<EvalState>(myArgs.searchPath, store);
+    auto state = std::make_unique<EvalState>(myArgs.searchPath, evalStore, store);
     state->repair = repair;
 
     auto autoArgs = myArgs.getAutoArgs(*state);
diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index 95903d882..a269c5b5c 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -153,6 +153,7 @@ static int main_nix_instantiate(int argc, char * * argv)
             settings.readOnlyMode = true;
 
         auto store = openStore();
+        auto evalStore = myArgs.evalStoreUrl ? openStore(*myArgs.evalStoreUrl) : store;
 
         auto state = std::make_unique<EvalState>(myArgs.searchPath, store);
         state->repair = repair;