diff --git a/src/include/port/win32_port.h b/src/include/port/win32_port.h
index 3d1de166cb0..7ffe5891c69 100644
--- a/src/include/port/win32_port.h
+++ b/src/include/port/win32_port.h
@@ -415,6 +415,11 @@ extern int	_pglstat64(const char *name, struct stat *buf);
 #undef ETIMEDOUT
 #define ETIMEDOUT WSAETIMEDOUT
 
+/*
+ * Supplement to <string.h>.
+ */
+#define strtok_r strtok_s
+
 /*
  * Locale stuff.
  *