diff --git a/osbuild/meta.py b/osbuild/meta.py
index 2a2f159e..c0edd0a6 100644
--- a/osbuild/meta.py
+++ b/osbuild/meta.py
@@ -68,7 +68,7 @@ class ValidationError:
             elif isinstance(p, int):
                 result += f"[{p}]"
             else:
-                assert "new type"
+                raise AssertionError("new type")
 
         return result