diff --git a/pkgs/build-support/trivial-builders.nix b/pkgs/build-support/trivial-builders.nix
index 93b8b1cbc428..fef91e1d89dc 100644
--- a/pkgs/build-support/trivial-builders.nix
+++ b/pkgs/build-support/trivial-builders.nix
@@ -48,7 +48,10 @@ rec {
 
   # Create a forest of symlinks to the files in `paths'.
   symlinkJoin = name: paths:
-    runCommand name { inherit paths; }
+    runCommand name
+      { inherit paths;
+        preferLocalBuild = true; allowSubstitutes = false;
+      }
       ''
         mkdir -p $out
         for i in $paths; do