diff --git a/jpeg/jdmerge.c b/jpeg/jdmerge.c
index 4d4424d9272f..5c83654af9dc 100644
--- a/jpeg/jdmerge.c
+++ b/jpeg/jdmerge.c
@@ -39,7 +39,7 @@
 
 #ifdef UPSAMPLE_MERGING_SUPPORTED
 
-#ifdef XP_WIN32
+#ifdef HAVE_MMX_INTEL_MNEMONICS
   __int64 const1 = 0x59BA0000D24B59BA;       // Cr_r Cr_b Cr_g Cr_r
   __int64 const2 = 0x00007168E9FA0000;		 // Cb-r Cb_b Cb_g Cb_r
   __int64 const5 = 0x0000D24B59BA0000;		 // Cr_b Cr_g Cr_r Cr_b
@@ -300,7 +300,7 @@ h2v1_merged_upsample (j_decompress_ptr cinfo,
  * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
  */
 
-#ifdef XP_WIN32
+#ifdef HAVE_MMX_INTEL_MNEMONICS
 __inline METHODDEF(void)
 h2v2_merged_upsample_orig (j_decompress_ptr cinfo,
 		      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
@@ -316,7 +316,7 @@ h2v2_merged_upsample (j_decompress_ptr cinfo,
 		      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
 		      JSAMPARRAY output_buf);
 
-#ifdef XP_WIN32
+#ifdef HAVE_MMX_INTEL_MNEMONICS
 METHODDEF(void)
 h2v2_merged_upsample (j_decompress_ptr cinfo,
 		      JSAMPIMAGE input_buf, JDIMENSION in_row_group_ctr,
diff --git a/jpeg/jidctfst.c b/jpeg/jidctfst.c
index 8e00287b2112..325514c9d3dc 100644
--- a/jpeg/jidctfst.c
+++ b/jpeg/jidctfst.c
@@ -38,6 +38,7 @@
 #include "jdct.h"		/* Private declarations for DCT subsystem */
 #include "xp_core.h"
 
+
 #ifdef DCT_IFAST_SUPPORTED
 
 
@@ -160,7 +161,7 @@
 #define IDESCALE(x,n)  ((int) IRIGHT_SHIFT(x, n))
 #endif
 
-#ifdef XP_WIN32
+#ifdef HAVE_MMX_INTEL_MNEMONICS
 __inline GLOBAL(void)
 jpeg_idct_ifast_mmx (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		 JCOEFPTR coef_block,
@@ -177,7 +178,7 @@ jpeg_idct_ifast(j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		 JSAMPARRAY output_buf, JDIMENSION output_col);
 
 
-#ifdef XP_WIN32
+#ifdef HAVE_MMX_INTEL_MNEMONICS
 GLOBAL(void)
 jpeg_idct_ifast (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 		 JCOEFPTR coef_block,
@@ -397,7 +398,7 @@ jpeg_idct_ifast (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 
 #endif
 
-#ifdef XP_WIN32
+#ifdef HAVE_MMX_INTEL_MNEMONICS
 
 
 _inline GLOBAL(void)
diff --git a/jpeg/jmorecfg.h b/jpeg/jmorecfg.h
index de7e3be41755..3a52fc2204fd 100644
--- a/jpeg/jmorecfg.h
+++ b/jpeg/jmorecfg.h
@@ -105,6 +105,11 @@ typedef short JSAMPLE;
 
 typedef short JCOEF;
 
+/* Defines for MMX support. */
+
+#if defined(XP_WIN32) && defined(_M_IX86)
+#define HAVE_MMX_INTEL_MNEMONICS 
+#endif
 
 /* Compressed datastreams are represented as arrays of JOCTET.
  * These must be EXACTLY 8 bits wide, at least once they are written to
diff --git a/jpeg/jpeglib.h b/jpeg/jpeglib.h
index 492994467a88..eb80b60b4858 100644
--- a/jpeg/jpeglib.h
+++ b/jpeg/jpeglib.h
@@ -15,10 +15,6 @@
 
 #include "xp_core.h"
 
-#ifdef XP_WIN32
-	extern int MMXAvailable;
-#endif
-
 /*
  * First we include the configuration files that record how this
  * installation of the JPEG library is set up.  jconfig.h can be
@@ -32,6 +28,11 @@
 #include "jmorecfg.h"		/* seldom changed options */
 
 
+#ifdef HAVE_MMX_INTEL_MNEMONICS
+	extern int MMXAvailable;
+#endif
+
+
 /* Version ID for the JPEG library.
  * Might be useful for tests like "#if JPEG_LIB_VERSION >= 60".
  */