1 files changed, 5 insertions, 0 deletions
diff --git a/Modules/_struct.c b/Modules/_struct.c
index 13d8072..5984bb6 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -1296,6 +1296,11 @@ prepare_s(PyStructObject *self)
     size_t ncodes;
 
     fmt = PyBytes_AS_STRING(self->s_format);
+    if (strlen(fmt) != (size_t)PyBytes_GET_SIZE(self->s_format)) {
+        PyErr_SetString(_structmodulestate_global->StructError,
+                        "embedded null character");
+        return -1;
+    }
 
     f = whichtable(&fmt);