Functions of fixed number of args are special-cased only for 3 or less args.
diff --git a/py/objfun.c b/py/objfun.c
index 1f6ad68..fe4f494 100644
--- a/py/objfun.c
+++ b/py/objfun.c
@@ -63,7 +63,7 @@
 
         return res;
 
-    } else if (self->n_args_min == self->n_args_max) {
+    } else if (self->n_args_min <= 3 && self->n_args_min == self->n_args_max) {
         // function requires a fixed number of arguments
 
         // dispatch function call