diff --git a/qr_encode.c b/qr_encode.c
index 52f3575..caa93bc 100644
--- a/qr_encode.c
+++ b/qr_encode.c
@@ -1,3 +1,4 @@
+#define PY_SSIZE_T_CLEAN
 #include <Python.h>
 #include <stdlib.h>
 #include <qrencode.h>