diff --git a/overlay.nix b/overlay.nix
index 52b0d17..a63363b 100644
--- a/overlay.nix
+++ b/overlay.nix
@@ -49,6 +49,11 @@ let
     wxparaver = callPackage ./pkgs/paraver/default.nix { };
   };
 
+  allPkgs = collect isDerivation bscPkgs;
+
+  mkStrict = pkg: if pkg ? overrideAttrs then pkg.overrideAttrs { strictDeps = true; } else pkg;
+  strictPkgs = map mkStrict allPkgs;
+
 in bscPkgs // {
   # Prevent accidental usage of bsc attribute
   bsc = throw "the bsc attribute is deprecated, packages are now in the root";
@@ -89,7 +94,7 @@ in bscPkgs // {
     };
 
     pkgs = final.runCommand "ci-pkgs" { }
-      "printf '%s\n' ${toString (collect isDerivation bscPkgs)} > $out";
+      "printf '%s\n' ${toString strictPkgs} > $out";
 
     tests = final.runCommand "ci-tests" { }
       "printf '%s\n' ${toString (collect isDerivation final.bsc-ci.test)} > $out";