diff --git a/libs/apr-util/xml/expat/lib/xmltok.c b/libs/apr-util/xml/expat/lib/xmltok.c
index e3fe3f788f..74c681f1e6 100644
--- a/libs/apr-util/xml/expat/lib/xmltok.c
+++ b/libs/apr-util/xml/expat/lib/xmltok.c
@@ -1225,7 +1225,7 @@ void unknown_toUtf8(const ENCODING *enc,
 		    const char **fromP, const char *fromLim,
 		    char **toP, const char *toLim)
 {
-  char buf[XML_UTF8_ENCODE_MAX];
+  char buf[XML_UTF8_ENCODE_MAX] = {0};
   for (;;) {
     const char *utf8;
     int n;