diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 5a803be..97d7796 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -273,7 +273,9 @@
 
     result = (PyByteArrayObject *) \
         PyByteArray_FromStringAndSize(NULL, va.len + vb.len);
-    if (result != NULL) {
+    // result->ob_bytes is NULL if result is an empty string:
+    // if va.len + vb.len equals zero.
+    if (result != NULL && result->ob_bytes != NULL) {
         memcpy(result->ob_bytes, va.buf, va.len);
         memcpy(result->ob_bytes + va.len, vb.buf, vb.len);
     }