diff --git a/pkgs/build-support/src-only/default.nix b/pkgs/build-support/src-only/default.nix
index 86fdda489077..d43bada43794 100644
--- a/pkgs/build-support/src-only/default.nix
+++ b/pkgs/build-support/src-only/default.nix
@@ -45,6 +45,8 @@ let
     // {
       name = "${name}-source";
 
+      outputs = [ "out" ];
+
       phases = [
         "unpackPhase"
         "patchPhase"