diff --git a/dom/plugins/ipc/PluginInstanceChild.cpp b/dom/plugins/ipc/PluginInstanceChild.cpp
index a36ff9bf7..c634b986c 100644
--- a/dom/plugins/ipc/PluginInstanceChild.cpp
+++ b/dom/plugins/ipc/PluginInstanceChild.cpp
@@ -257,7 +257,8 @@ PluginInstanceChild::DoNPP_New()
 
     Initialize();
 
-#if defined(XP_MACOSX) && defined(__i386__)
+#if 0
+//#if defined(XP_MACOSX) && defined(__i386__)
     // If an i386 Mac OS X plugin has selected the Carbon event model then
     // we have to fail. We do not support putting Carbon event model plugins
     // out of process. Note that Carbon is the default model so out of process
diff --git a/gfx/2d/ScaledFontMac.cpp b/gfx/2d/ScaledFontMac.cpp
index 45343d6ec..1d8378aae 100644
--- a/gfx/2d/ScaledFontMac.cpp
+++ b/gfx/2d/ScaledFontMac.cpp
@@ -218,6 +218,12 @@ struct writeBuf
     int offset;
 };
 
+#ifdef __ppc__
+#define TAG_CFF 0x43464620
+#else
+#define TAG_CFF 0x20464643
+#endif
+
 bool
 ScaledFontMac::GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton)
 {
@@ -233,7 +239,7 @@ ScaledFontMac::GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton)
     bool CFF = false;
     for (CFIndex i = 0; i<count; i++) {
         uint32_t tag = (uint32_t)(uintptr_t)CFArrayGetValueAtIndex(tags, i);
-        if (tag == 0x43464620) // 'CFF '
+        if (tag == TAG_CFF) // 'CFF '
             CFF = true;
         CFDataRef data = CGFontCopyTableForTag(mFont, tag);
         records[i].tag = tag;
@@ -283,11 +289,8 @@ ScaledFontMac::GetFontFileData(FontFileDataOutput aDataCallback, void *aBaton)
     uint32_t *wtable = (reinterpret_cast<uint32_t *>(table.Elements()));
     TableRecord *records = new TableRecord[count];
     for (uint32_t i=3; i<(sizer/4); i+=4) { // Skip header
-#ifndef __ppc__
-#error need little-endian version
-#endif
         uint32_t tag = wtable[i];
-        if (tag == 0x43464620) // 'CFF '
+        if (tag == TAG_CFF)
             CFF = true;
         // We know the length from the directory, so we can simply import
         // the data. We assume the table exists, and OMG if it doesn't.
diff --git a/gfx/thebes/gfxMacPlatformFontList.mm b/gfx/thebes/gfxMacPlatformFontList.mm
index d38ded97c..75abc38af 100644
--- a/gfx/thebes/gfxMacPlatformFontList.mm
+++ b/gfx/thebes/gfxMacPlatformFontList.mm
@@ -488,7 +488,7 @@ MacOSFontEntry::GetFontTable(uint32_t aTag)
     if (MOZ_LIKELY(mFontTableDirSize > 0)) {
         // XXX: This assumes big endian (warning Intel)
 #ifndef __ppc__
-#error needs GetFontTable fast path needs little endian version
+#warning needs GetFontTable fast path needs little endian version
 #endif
 
 #ifdef DEBUG_X
diff --git a/modules/woff2/src/port.h b/modules/woff2/src/port.h
index fcecbe775..4e3a87270 100644
--- a/modules/woff2/src/port.h
+++ b/modules/woff2/src/port.h
@@ -72,8 +72,10 @@ inline int Log2Floor(uint32 n) {
 #endif  /* endianness */
 #endif  /* CPU whitelist */
 
+#if !defined(__i386) && !defined(__x86_64__)
 #ifndef WOFF_BIG_ENDIAN
 #error unexpected endianness
 #endif
+#endif /* !defined(__i386) && !defined(__x86_64__) */
 
 #endif  // WOFF2_PORT_H_
diff --git a/toolkit/xre/nsSigHandlers.cpp b/toolkit/xre/nsSigHandlers.cpp
index 000129004..73674d406 100644
--- a/toolkit/xre/nsSigHandlers.cpp
+++ b/toolkit/xre/nsSigHandlers.cpp
@@ -37,6 +37,14 @@
 #include <ucontext.h>
 #endif
 
+#ifdef XP_MACOSX
+#ifndef __ppc__
+#include <sys/ucontext.h>
+#include <mach/mach_types.h>
+#include <mach/thread_status.h>
+#endif
+#endif
+
 static char _progname[1024] = "huh?";
 
 // Note: some tests manipulate this value.
@@ -160,14 +168,14 @@ static void fpehandler(int signum, siginfo_t *si, void *context)
   ucontext_t *uc = (ucontext_t *)context;
 
 #if defined(__i386__) || defined(__amd64__)
-  _STRUCT_FP_CONTROL *ctrl = &uc->uc_mcontext->__fs.__fpu_fcw;
-  ctrl->__invalid = ctrl->__denorm = ctrl->__zdiv = ctrl->__ovrfl = ctrl->__undfl = ctrl->__precis = 1;
+  fp_control *ctrl = &uc->uc_mcontext->fs.fpu_fcw;
+  ctrl->invalid = ctrl->denorm = ctrl->zdiv = ctrl->ovrfl = ctrl->undfl = ctrl->precis = 1;
 
-  _STRUCT_FP_STATUS *status = &uc->uc_mcontext->__fs.__fpu_fsw;
-  status->__invalid = status->__denorm = status->__zdiv = status->__ovrfl = status->__undfl =
-    status->__precis = status->__stkflt = status->__errsumm = 0;
+  fp_status *status = &uc->uc_mcontext->fs.fpu_fsw;
+  status->invalid = status->denorm = status->zdiv = status->ovrfl = status->undfl =
+    status->precis = status->stkflt = status->errsumm = 0;
 
-  uint32_t *mxcsr = &uc->uc_mcontext->__fs.__fpu_mxcsr;
+  uint32_t *mxcsr = &uc->uc_mcontext->fs.fpu_mxcsr;
   *mxcsr |= SSE_EXCEPTION_MASK; /* disable all SSE exceptions */
   *mxcsr &= ~SSE_STATUS_FLAGS; /* clear all pending SSE exceptions */
 #endif
diff --git a/xpcom/string/nsUTF8Utils.h b/xpcom/string/nsUTF8Utils.h
index 41747f0d4..f121c514b 100644
--- a/xpcom/string/nsUTF8Utils.h
+++ b/xpcom/string/nsUTF8Utils.h
@@ -12,7 +12,8 @@
 
 #include "nscore.h"
 #include "mozilla/Assertions.h"
-#if MOZILLA_MAY_SUPPORT_SSE2
+
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
 #include "mozilla/SSE.h"
 #endif
 
diff --git a/xpcom/threads/nsProcessCommon.cpp b/xpcom/threads/nsProcessCommon.cpp
index 82170b247..ed4390e45 100644
--- a/xpcom/threads/nsProcessCommon.cpp
+++ b/xpcom/threads/nsProcessCommon.cpp
@@ -48,6 +48,7 @@ using namespace mozilla;
 #ifdef XP_MACOSX
 typedef int cpu_type_t; // we don't have cpu_type* on 10.4.
 #define CPU_TYPE_ANY           ((cpu_type_t) -1)
+#define CPU_TYPE_X86           ((cpu_type_t)  7)
 #define CPU_TYPE_POWERPC       ((cpu_type_t) 18)
 
 cpu_type_t pref_cpu_types[2] = {