diff --git a/pkgs/by-name/le/lean4/package.nix b/pkgs/by-name/le/lean4/package.nix
index 8d98ebd2c356..17913e8b1181 100644
--- a/pkgs/by-name/le/lean4/package.nix
+++ b/pkgs/by-name/le/lean4/package.nix
@@ -93,6 +93,7 @@ stdenv.mkDerivation (finalAttrs: {
     "-DUSE_GITHASH=OFF"
     "-DINSTALL_LICENSE=OFF"
     "-DINSTALL_CADICAL=OFF"
+    "-DSTAGE1_CMAKE_INSTALL_PREFIX=${placeholder "out"}"
     "-DUSE_MIMALLOC=${if enableMimalloc then "ON" else "OFF"}"
   ];
 
diff --git a/pkgs/development/lean-modules/lean4/default.nix b/pkgs/development/lean-modules/lean4/default.nix
index 3f62f6151b8f..d9ce64b4f591 100644
--- a/pkgs/development/lean-modules/lean4/default.nix
+++ b/pkgs/development/lean-modules/lean4/default.nix
@@ -95,6 +95,7 @@ let
       "-DINSTALL_LICENSE=OFF"
       "-DINSTALL_CADICAL=OFF"
       "-DINSTALL_LEANTAR=OFF"
+      "-DSTAGE1_CMAKE_INSTALL_PREFIX=${placeholder "out"}"
       "-DUSE_MIMALLOC=ON"
     ];