diff --git a/Python/ceval.c b/Python/ceval.c
index ca38c682c33c3b75a0e2133cb98c13fb3af46fe8..ce4b67a7b5be1ed27a0526b5876f12a5e38ea2bf 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -775,11 +775,7 @@ eval_code2(PyCodeObject *co, PyObject *globals, PyObject *locals,
 				PUSH(x);
 				continue;
 			default:
-				fprintf(stderr, "Invalid argument to DUP_TOPX: %d!\n", oparg);
-				PyErr_SetString(PyExc_SystemError,
-					"invalid argument to DUP_TOPX");
-				x = NULL;
-				break;
+				Py_FatalError("invalid argument to DUP_TOPX (bytecode corruption?)");
 			}
 			break;