diff --git a/Include/patchlevel.h b/Include/patchlevel.h
index 3fe9d1bbb48..601b951bedd 100644
--- a/Include/patchlevel.h
+++ b/Include/patchlevel.h
@@ -23,7 +23,7 @@
 #define PY_RELEASE_SERIAL       0
 
 /* Version as a string */
-#define PY_VERSION              "3.9.21"
+#define PY_VERSION              "3.9.21+"
 /*--end constants--*/
 
 /* Version as a single 4-byte hex number, e.g. 0x010502B2 == 1.5.2b2.