diff --git a/jdhuff.h b/jdhuff.h
index ac6e0e58..60d8e8b0 100644
--- a/jdhuff.h
+++ b/jdhuff.h
@@ -4,7 +4,7 @@
  * This file was part of the Independent JPEG Group's software:
  * Copyright (C) 1991-1997, Thomas G. Lane.
  * libjpeg-turbo Modifications:
- * Copyright (C) 2010-2011, 2015-2016, D. R. Commander.
+ * Copyright (C) 2010-2011, 2015-2016, 2021, D. R. Commander.
  * Copyright (C) 2018, Matthias Räncker.
  * For conditions of distribution and use, see the accompanying README.ijg
  * file.
@@ -234,7 +234,10 @@ slowlabel: \
       s |= GET_BITS(1); \
       nb++; \
     } \
-    s = htbl->pub->huffval[(int)(s + htbl->valoffset[nb]) & 0xFF]; \
+    if (nb > 16) \
+      s = 0; \
+    else \
+      s = htbl->pub->huffval[(int)(s + htbl->valoffset[nb])]; \
   }
 
 /* Out-of-line case for Huffman code fetching */