diff --git a/ext/mysqlnd/mysqlnd_portability.h b/ext/mysqlnd/mysqlnd_portability.h
index 37aeb67e216..20a2a48c434 100644
--- a/ext/mysqlnd/mysqlnd_portability.h
+++ b/ext/mysqlnd/mysqlnd_portability.h
@@ -280,6 +280,7 @@ typedef union {
                                (((uint32) ((uchar) (A)[1])) << 8) +\
                                (((uint32) ((uchar) (A)[2])) << 16) +\
                                (((uint32) ((uchar) (A)[3])) << 24))
+#undef bit_uint5korr
 #define bit_uint5korr(A)  ((ulonglong)(((uint32) ((uchar) (A)[0])) +\
                                   (((uint32) ((uchar) (A)[1])) << 8) +\
                                   (((uint32) ((uchar) (A)[2])) << 16) +\