diff --git a/lib/types.nix b/lib/types.nix
index de3c4f0d6030..d177dda41245 100644
--- a/lib/types.nix
+++ b/lib/types.nix
@@ -242,8 +242,7 @@ rec {
 
     path = mkOptionType {
       name = "path";
-      # Hacky: there is no ‘isPath’ primop.
-      check = x: builtins.substring 0 1 (toString x) == "/";
+      check = x: isCoercibleToString x && builtins.substring 0 1 (toString x) == "/";
       merge = mergeEqualOption;
     };