diff --git a/tools/schemapi/vega_expr.py b/tools/schemapi/vega_expr.py
index 5aa6ce9d0..2f0582a49 100644
--- a/tools/schemapi/vega_expr.py
+++ b/tools/schemapi/vega_expr.py
@@ -149,7 +149,9 @@ def with_doc(self) -> Self:
     @functools.cached_property
     def parameter_names(self) -> frozenset[str]:
         if self.parameters:
-            return frozenset(param.name for param in self.parameters)
+            return frozenset(
+                param.name for param in self.parameters if not param.variadic
+            )
         else:
             msg = (
                 f"Cannot provide `parameter_names` until they have been initialized via:\n"