diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index c02f1b2..705be07 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -599,6 +599,8 @@
 		PyErr_BadInternalCall();
 		return -1;
 	}
+	assert(key);
+	assert(value);
 	mp = (dictobject *)op;
 	if (PyString_CheckExact(key)) {
 		hash = ((PyStringObject *)key)->ob_shash;
@@ -647,6 +649,7 @@
 		PyErr_BadInternalCall();
 		return -1;
 	}
+	assert(key);
 	if (!PyString_CheckExact(key) ||
 	    (hash = ((PyStringObject *) key)->ob_shash) == -1) {
 		hash = PyObject_Hash(key);