--- /usr/src/asterisk-11.20.0/include/asterisk/strings.h.org	2015-12-19 15:21:06.087506460 +0000
+++ /usr/src/asterisk-11.20.0/include/asterisk/strings.h	2015-12-19 15:27:25.243372739 +0000
@@ -469,7 +469,7 @@
 	if (!buf) {
 		return;
 	}
-	while (buf->__AST_STR_USED && buf->__AST_STR_STR[buf->__AST_STR_USED - 1] < 33) {
+	while (buf->__AST_STR_USED && ((unsigned char) buf->__AST_STR_STR[buf->__AST_STR_USED - 1]) < 33) {
 		buf->__AST_STR_STR[--(buf->__AST_STR_USED)] = '\0';
 	}
 }