diff --git a/test/backend/test_stunning.py b/test/backend/test_stunning.py
index 4d9e966a77..28c4499946 100644
--- a/test/backend/test_stunning.py
+++ b/test/backend/test_stunning.py
@@ -25,7 +25,7 @@ class TestStunning(unittest.TestCase):
     nv = a[12].cat(a[76]).tolist()
 
     vi = Variable('i', 0, a.shape[0]-1)
-    with self.assertRaisesRegex(AssertionError, "bind mismatch on"):
+    with self.assertRaisesRegex(RuntimeError, "bind mismatch on"):
       wv = a[vi.bind(12)].cat(a[vi.bind(76)]).tolist()
       self.assertListEqual(nv, wv)
 
diff --git a/tinygrad/engine/schedule.py b/tinygrad/engine/schedule.py
index e2ae4dfbe3..cbaa9f0848 100644
--- a/tinygrad/engine/schedule.py
+++ b/tinygrad/engine/schedule.py
@@ -148,7 +148,7 @@ def complete_create_schedule_with_vars(big_sink:UOp) -> tuple[list[ExecItem], di
       nm = b.src[0].expr
       if nm not in used_vars: continue
       val = b.src[1].arg
-      assert nm not in var_vals or var_vals[nm] == val, f"bind mismatch on {nm}, {var_vals[nm]} != {val}"
+      if var_vals.get(nm, val) != val: raise RuntimeError(f"bind mismatch on {nm}, {var_vals[nm]} != {val}")
       var_vals[nm] = val
 
   # convert LINEAR to ExecItems