diff --git a/pkgs/by-name/op/openapi-generator-cli/example.nix b/pkgs/by-name/op/openapi-generator-cli/example.nix
index fd30077713c6..df085b9338d9 100644
--- a/pkgs/by-name/op/openapi-generator-cli/example.nix
+++ b/pkgs/by-name/op/openapi-generator-cli/example.nix
@@ -11,11 +11,12 @@ runCommand "openapi-generator-cli-test"
       url = "https://raw.githubusercontent.com/OAI/OpenAPI-Specification/14c0908becbccd78252be49bd92be8c53cd2b9e3/examples/v3.0/petstore.yaml";
       hash = "sha256-q2D1naR41KwxLNn6vMbL0G+Pl1q4oaDCApsqQfZf7dU=";
     };
-    config = builtins.toJSON {
-      elmVersion = "0.19";
-      elmPrefixCustomTypeVariants = false;
-    };
-    passAsFile = [ "config" ];
+    config = builtins.toFile "config.json" (
+      builtins.toJSON {
+        elmVersion = "0.19";
+        elmPrefixCustomTypeVariants = false;
+      }
+    );
   }
   ''
     openapi-generator-cli generate \