diff --git a/ChangeLog.txt b/ChangeLog.txt
index 139bcca5..3711188c 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -32,6 +32,11 @@ SIMD-enabled libjpeg-turbo MIPS build was executed with the -nosmooth option on
 a MIPS machine that lacked DSPr2 support.  The MIPS SIMD routines for h2v1 and
 h2v2 merged upsampling were not properly checking for the existence of DSPr2.
 
+[6] Performance has been improved significantly on 64-bit Mac platforms
+(particularly compression performance.)  Due to an oversight, the 64-bit
+version of the accelerated Huffman codec was not being compiled in when
+libjpeg-turbo was built on OS X.  Oops.
+
 
 1.4.0
 =====
diff --git a/jchuff.c b/jchuff.c
index a5c0a1fd..fe03591d 100644
--- a/jchuff.c
+++ b/jchuff.c
@@ -21,6 +21,7 @@
 #include "jpeglib.h"
 #include "jchuff.h"             /* Declarations shared with jcphuff.c */
 #include <limits.h>
+#include <stdint.h>
 
 /*
  * NOTE: If USE_CLZ_INTRINSIC is defined, then clz/bsr instructions will be
@@ -376,6 +377,10 @@ dump_buffer (working_state * state)
   } \
 }
 
+#if !defined(_WIN32) && !defined(__WORDSIZE)
+#error __WORDSIZE is not defined
+#endif
+
 #if __WORDSIZE==64 || defined(_WIN64)
 
 #define EMIT_BITS(code, size) { \
diff --git a/jdhuff.c b/jdhuff.c
index 7dc13289..583ee114 100644
--- a/jdhuff.c
+++ b/jdhuff.c
@@ -22,6 +22,7 @@
 #include "jdhuff.h"             /* Declarations shared with jdphuff.c */
 #include "jpegcomp.h"
 #include "jstdhuff.c"
+#include <stdint.h>
 
 
 /*
@@ -419,6 +420,10 @@ jpeg_fill_bit_buffer (bitread_working_state * state,
   } \
 }
 
+#if !defined(_WIN32) && !defined(__WORDSIZE)
+#error __WORDSIZE is not defined
+#endif
+
 #if __WORDSIZE == 64 || defined(_WIN64)
 
 /* Pre-fetch 48 bytes, because the holding register is 64-bit */