diff --git a/scripts/dtc/pylibfdt/libfdt.i_shipped b/scripts/dtc/pylibfdt/libfdt.i_shipped
index 27c29ea..56cc5d4 100644
--- a/scripts/dtc/pylibfdt/libfdt.i_shipped
+++ b/scripts/dtc/pylibfdt/libfdt.i_shipped
@@ -7,6 +7,10 @@
 
 %module libfdt
 
+%begin %{
+#define PY_SSIZE_T_CLEAN
+%}
+
 %include <stdint.i>
 
 %{