diff --git a/gfx/qcms/iccread.c b/gfx/qcms/iccread.c
index af548892b9f1..c721fbe1988e 100644
--- a/gfx/qcms/iccread.c
+++ b/gfx/qcms/iccread.c
@@ -29,17 +29,13 @@
 typedef uint32_t __be32;
 typedef uint16_t __be16;
 
-#if !defined(BIG_ENDIAN) && !defined(LITTLE_ENDIAN)
-#error Unknown endianess
-#endif
-
 #if 0
 not used yet
 /* __builtin_bswap isn't available in older gccs
  * so open code it for now */
 static __be32 cpu_to_be32(int32_t v)
 {
-#ifdef LITTLE_ENDIAN
+#ifdef IS_LITTLE_ENDIAN
 	return ((v & 0xff) << 24) | ((v & 0xff00) << 8) | ((v & 0xff0000) >> 8) | ((v & 0xff000000) >> 24);
 	//return __builtin_bswap32(v);
 	return v;
@@ -49,7 +45,7 @@ static __be32 cpu_to_be32(int32_t v)
 
 static uint32_t be32_to_cpu(__be32 v)
 {
-#ifdef LITTLE_ENDIAN
+#ifdef IS_LITTLE_ENDIAN
 	return ((v & 0xff) << 24) | ((v & 0xff00) << 8) | ((v & 0xff0000) >> 8) | ((v & 0xff000000) >> 24);
 	//return __builtin_bswap32(v);
 #else
@@ -59,7 +55,7 @@ static uint32_t be32_to_cpu(__be32 v)
 
 static uint32_t be16_to_cpu(__be16 v)
 {
-#ifdef LITTLE_ENDIAN
+#ifdef IS_LITTLE_ENDIAN
 	return ((v & 0xff) << 8) | ((v & 0xff00) >> 8);
 #else
 	return v;
diff --git a/gfx/qcms/qcmstypes.h b/gfx/qcms/qcmstypes.h
index d81e985cae6f..25ffa57a0a11 100644
--- a/gfx/qcms/qcmstypes.h
+++ b/gfx/qcms/qcmstypes.h
@@ -5,15 +5,7 @@
 
 #include "prtypes.h"
 
-#if !defined(BIG_ENDIAN) && !defined(LITTLE_ENDIAN)
-#ifdef IS_LITTLE_ENDIAN
-#define LITTLE_ENDIAN
-#endif
-
-#ifdef IS_BIG_ENDIAN
-#define BIG_ENDIAN
-#endif
-#endif
+/* prtypes.h defines IS_LITTLE_ENDIAN and IS_BIG ENDIAN */
 
 #if defined (__SVR4) && defined (__sun)
 /* int_types.h gets included somehow, so avoid redefining the types differently */
@@ -40,14 +32,24 @@ typedef PRUptrdiff uintptr_t;
 
 #else // MOZ_QCMS
 
+#if BYTE_ORDER == LITTLE_ENDIAN
+#define IS_LITTLE_ENDIAN
+#elif BYTE_ORDER == BIG_ENDIAN
+#define IS_BIG_ENDIAN
+#endif
+
 /* all of the platforms that we use _MSC_VER on are little endian
  * so this is sufficient for now */
 #ifdef _MSC_VER
-#define LITTLE_ENDIAN
+#define IS_LITTLE_ENDIAN
 #endif
 
 #ifdef __OS2__
-#define LITTLE_ENDIAN
+#define IS_LITTLE_ENDIAN
+#endif
+
+#if !defined(IS_LITTLE_ENDIAN) && !defined(IS_BIG_ENDIAN)
+#error Unknown endianess
 #endif
 
 #if defined (_SVR4) || defined (SVR4) || defined (__OpenBSD__) || defined (_sgi) || defined (__sun) || defined (sun) || defined (__digital__)