diff --git a/formats/format_jpeg.c b/formats/format_jpeg.c
index d71aeec801..96fed0deab 100644
--- a/formats/format_jpeg.c
+++ b/formats/format_jpeg.c
@@ -55,7 +55,7 @@ static struct ast_frame *jpeg_read_image(int fd, int len)
 	struct ast_frame fr;
 	int res;
 	char buf[65536];
-	if (len > sizeof(buf)) {
+	if (len > sizeof(buf) || len < 0) {
 		ast_log(LOG_WARNING, "JPEG image too large to read\n");
 		return NULL;
 	}