diff --git a/release.nix b/release.nix
index 65a4bc2..2afb964 100644
--- a/release.nix
+++ b/release.nix
@@ -104,7 +104,7 @@ in let
           ( builtins.map
               ( name: { inherit name; value = valueSet.${name}; } )
               ( pkgs.lib.filter
-                  ( name: pkgs.lib.isDerivation valueSet.${name} )
+                  ( name: ( builtins.tryEval (pkgs.lib.isDerivation valueSet.${name}) ).value )
                   ( pkgs.lib.attrNames nameSet ) ) );
 
       # Provided overlays