diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index 4fd7377c..d65e96a3 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -88,7 +88,7 @@ sub getGCRootsDir {
 
 sub gcRootFor {
     my ($path) = @_;
-    return getGCRootsDir . basename $path;
+    return getGCRootsDir . "/" . basename $path;
 }