diff --git a/httpd/httpd.c b/httpd/httpd.c
index 7b90adf..561bd93 100644
--- a/httpd/httpd.c
+++ b/httpd/httpd.c
@@ -272,7 +272,8 @@ __xdata uint8_t *scan_header(__xdata uint8_t *p)
 		dbg_string("\nFound multipart\n");
 		content_type += 30;
 		uint8_t i = 0;
-		while (content_type[i] != '\r' && content_type[i] != '\n') {
+		while (i < (sizeof(boundary) - 5) &&
+				content_type[i] != '\r' && content_type[i] != '\n') {
 			boundary[i + 4] = content_type[i];
 			i++;
 		}