diff --git a/src/client/mac/Framework/Breakpad.mm b/src/client/mac/Framework/Breakpad.mm
index 9de0a94b..65678807 100644
--- a/src/client/mac/Framework/Breakpad.mm
+++ b/src/client/mac/Framework/Breakpad.mm
@@ -39,20 +39,20 @@
 #define DEBUGLOG if (gDebugLog) fprintf
 #define IGNORE_DEBUGGER "BREAKPAD_IGNORE_DEBUGGER"
 
-#import "client/mac/Framework/Breakpad.h"
-#import "client/mac/crash_generation/Inspector.h"
-#import "client/mac/Framework/OnDemandServer.h"
-#import "client/mac/handler/protected_memory_allocator.h"
 #import "common/mac/MachIPC.h"
 #import "common/mac/SimpleStringDictionary.h"
 
+#import "client/mac/crash_generation/Inspector.h"
+#import "client/mac/handler/exception_handler.h"
+#import "client/mac/Framework/Breakpad.h"
+#import "client/mac/Framework/OnDemandServer.h"
+#import "client/mac/handler/protected_memory_allocator.h"
+
 #import <sys/stat.h>
 #import <sys/sysctl.h>
 
 #import <Foundation/Foundation.h>
 
-#import "exception_handler.h"
-#import "string_utilities.h"
 
 using google_breakpad::KeyValueEntry;
 using google_breakpad::SimpleStringDictionary;
diff --git a/src/client/mac/handler/minidump_generator.cc b/src/client/mac/handler/minidump_generator.cc
index 75c32ebc..b3091d4d 100644
--- a/src/client/mac/handler/minidump_generator.cc
+++ b/src/client/mac/handler/minidump_generator.cc
@@ -418,9 +418,9 @@ bool MinidumpGenerator::WriteStack(breakpad_thread_state_data_t state,
     reinterpret_cast<breakpad_thread_state_t *>(state);
 
 #if TARGET_CPU_X86_64
-  mach_vm_address_t start_addr = machine_state->__rsp;
+  mach_vm_address_t start_addr = REGISTER_FROM_THREADSTATE(machine_state, rsp);
 #else
-  mach_vm_address_t start_addr = machine_state->esp;
+  mach_vm_address_t start_addr = REGISTER_FROM_THREADSTATE(machine_state, esp);
 #endif
   return WriteStackFromStartAddress(start_addr, stack_location);
 }
@@ -431,9 +431,9 @@ MinidumpGenerator::CurrentPCForStack(breakpad_thread_state_data_t state) {
     reinterpret_cast<breakpad_thread_state_t *>(state);
 
 #if TARGET_CPU_X86_64
-  return machine_state->__rip;
+  return REGISTER_FROM_THREADSTATE(machine_state, rip);
 #else
-  return machine_state->eip;
+  return REGISTER_FROM_THREADSTATE(machine_state, eip);
 #endif
 }
 
@@ -449,10 +449,9 @@ bool MinidumpGenerator::WriteContext(breakpad_thread_state_data_t state,
   *register_location = context.location();
   MinidumpContext *context_ptr = context.get();
 
+#define AddReg(a) context_ptr->a = REGISTER_FROM_THREADSTATE(machine_state, a)
 #if TARGET_CPU_X86
   context_ptr->context_flags = MD_CONTEXT_X86;
-
-#define AddReg(a) context_ptr->a = machine_state->a
   AddReg(eax);
   AddReg(ebx);
   AddReg(ecx);
@@ -472,8 +471,6 @@ bool MinidumpGenerator::WriteContext(breakpad_thread_state_data_t state,
 
   AddReg(eip);
 #else
-
-#define AddReg(a) context_ptr->a = machine_state->__ ## a
   context_ptr->context_flags = MD_CONTEXT_AMD64;
   AddReg(rax);
   AddReg(rbx);
@@ -501,6 +498,7 @@ bool MinidumpGenerator::WriteContext(breakpad_thread_state_data_t state,
   AddReg(fs);
   AddReg(gs);
 #endif
+#undef AddReg(a)
 
   return true;
 }
diff --git a/src/client/mac/handler/minidump_generator.h b/src/client/mac/handler/minidump_generator.h
index 0d3424c3..6a06ed66 100644
--- a/src/client/mac/handler/minidump_generator.h
+++ b/src/client/mac/handler/minidump_generator.h
@@ -66,6 +66,18 @@ typedef ppc_thread_state_t breakpad_thread_state_t;
 typedef MDRawContextPPC MinidumpContext;
 #endif
 
+// Use the REGISTER_FROM_THREADSTATE to access a register name from the
+// breakpad_thread_state_t structure.
+#if __DARWIN_UNIX03 || !TARGET_CPU_X86 || TARGET_CPU_X86_64
+// In The 10.5 SDK Headers Apple prepended __ to the variable names in the
+// i386_thread_state_t structure.  There's no good way to tell what version of
+// the SDK we're compiling against so we just toggle on the same preprocessor
+// symbol Apple's headers use.
+#define REGISTER_FROM_THREADSTATE(a, b) ((a)->__ ## b)
+#else
+#define REGISTER_FROM_THREADSTATE(a, b) (a->b)
+#endif
+
 // Creates a minidump file of the current process.  If there is exception data,
 // use SetExceptionInformation() to add this to the minidump.  The minidump
 // file is generated by the Write() function.