1 files changed, 5 insertions, 1 deletions
diff --git a/Python/peephole.c b/Python/peephole.c
index baa217ad02..84de1abc17 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -511,8 +511,12 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
         if (instrsize(j) > ilen) {
             goto exitUnchanged;
         }
-        assert(ilen <= INT_MAX);
         /* If instrsize(j) < ilen, we'll emit EXTENDED_ARG 0 */
+        if (ilen > 4) {
+            /* Can only happen when PyCode_Optimize() is called with
+               malformed bytecode. */
+            goto exitUnchanged;
+        }
         write_op_arg(codestr + h, opcode, j, (int)ilen);
         h += ilen;
     }