diff --git a/channels/chan_modem_i4l.c b/channels/chan_modem_i4l.c
index 3d0cbf26b4..69aa004547 100755
--- a/channels/chan_modem_i4l.c
+++ b/channels/chan_modem_i4l.c
@@ -329,7 +329,7 @@ static struct ast_frame *i4l_handle_escape(struct ast_modem_pvt *p, char esc)
 
 static struct ast_frame *i4l_read(struct ast_modem_pvt *p)
 {
-	char result[256];
+	unsigned char result[256];
 	short *b;
 	struct ast_frame *f=NULL;
 	int res;