diff --git a/gdtoa/CMakeLists.txt b/gdtoa/CMakeLists.txt
index 9403f17935..7a1304d0f2 100644
--- a/gdtoa/CMakeLists.txt
+++ b/gdtoa/CMakeLists.txt
@@ -15,7 +15,7 @@ endif( "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" OR "${CMAKE_CXX_COMPILER_ID}" S
 include_directories( ${CMAKE_CURRENT_BINARY_DIR} )
 add_definitions( -DINFNAN_CHECK -DMULTIPLE_THREADS )
 
-if( NOT MSVC )
+if( NOT MSVC AND NOT APPLE )
 	if( NOT CMAKE_CROSSCOMPILING )
 		add_executable( arithchk arithchk.c )
 	endif( NOT CMAKE_CROSSCOMPILING )
@@ -35,7 +35,7 @@ if( NOT MSVC )
 		
 	set( GEN_FP_FILES arith.h gd_qnan.h )
 	set( GEN_FP_DEPS ${CMAKE_CURRENT_BINARY_DIR}/arith.h ${CMAKE_CURRENTY_BINARY_DIR}/gd_qnan.h )
-endif( NOT MSVC )
+endif( NOT MSVC AND NOT APPLE )
 
 add_library( gdtoa
 	${GEN_FP_FILES}
diff --git a/gdtoa/gdtoa.h b/gdtoa/gdtoa.h
index 95132294e7..2707ff7df3 100644
--- a/gdtoa/gdtoa.h
+++ b/gdtoa/gdtoa.h
@@ -32,7 +32,7 @@ THIS SOFTWARE.
 #ifndef GDTOA_H_INCLUDED
 #define GDTOA_H_INCLUDED
 
-#ifdef _MSC_VER
+#if defined(_MSC_VER)
 /* [RH] Generating arith.h strikes me as too cumbersome under Visual
  * Studio, so here's the equivalent, given the limited number of
  * architectures that MSC can target. (Itanium? Who cares about that?)
@@ -43,6 +43,26 @@ THIS SOFTWARE.
 #ifdef _M_X64
 #define X64_bit_pointers
 #endif
+#elif defined(__APPLE__)
+/* [BL] While generating the files may be easy, on OS X we have cross
+ * compiling to deal with, which means we can't run the generation
+ * program on the target.
+ */
+#if defined(__x86_64__)
+#define IEEE_8087
+#define Arith_Kind_ASL 1
+#define Long int
+#define Intcast (int)(long)
+#define Double_Align
+#define X64_bit_pointers
+#elif defined(__i386__)
+#define IEEE_8087
+#define Arith_Kind_ASL 1
+#else
+#define IEEE_MC68k
+#define Arith_Kind_ASL 2
+#define Double_Align
+#endif
 #else
 #include "arith.h"
 #endif
diff --git a/gdtoa/gdtoaimp.h b/gdtoa/gdtoaimp.h
index 023d97062b..f93e03ef56 100644
--- a/gdtoa/gdtoaimp.h
+++ b/gdtoa/gdtoaimp.h
@@ -167,7 +167,7 @@ THIS SOFTWARE.
 #define GDTOAIMP_H_INCLUDED
 #include "gdtoa.h"
 
-#ifdef _MSC_VER
+#if defined(_MSC_VER)
 /* [RH] Generating gd_qnan.h strikes me as too cumbersome under Visual
  * Studio, so here's the equivalent, given the limited number of
  * architectures that MSC can target. (Itanium? Who cares about that?)
@@ -188,6 +188,34 @@ THIS SOFTWARE.
  * it turns out that it has a true long double type. I thought that
  * all ia32 compilers had phased out extended precision.
  */
+#elif defined(__APPLE__)
+#if defined(__x86_64__) || defined(__i386__)
+#define f_QNAN 0xffc00000
+#define d_QNAN0 0x0
+#define d_QNAN1 0xfff80000
+#define ld_QNAN0 0x0
+#define ld_QNAN1 0xc0000000
+#define ld_QNAN2 0xffff
+#define ld_QNAN3 0x0
+#define ldus_QNAN0 0x0
+#define ldus_QNAN1 0x0
+#define ldus_QNAN2 0x0
+#define ldus_QNAN3 0xc000
+#define ldus_QNAN4 0xffff
+#else
+#define f_QNAN 0xffc00000
+#define d_QNAN0 0xfff80000
+#define d_QNAN1 0x0
+#define ld_QNAN0 0xfff80000
+#define ld_QNAN1 0x0
+#define ld_QNAN2 0x0
+#define ld_QNAN3 0x0
+#define ldus_QNAN0 0xfff8
+#define ldus_QNAN1 0x0
+#define ldus_QNAN2 0x0
+#define ldus_QNAN3 0x0
+#define ldus_QNAN4 0x0
+#endif
 #else
 #include "gd_qnan.h"
 #endif