diff --git a/src/core/jpg.js b/src/core/jpg.js
index 350d6953c..26de99603 100644
--- a/src/core/jpg.js
+++ b/src/core/jpg.js
@@ -159,6 +159,9 @@ var JpegImage = (function jpegImage() {
     }
 
     function receiveAndExtend(length) {
+      if (length === 1) {
+        return readBit() === 1 ? 1 : -1;
+      }
       var n = receive(length);
       if (n >= 1 << (length - 1)) {
         return n;