diff --git a/include/stddef.h b/include/stddef.h
index f856119..773006f 100644
--- a/include/stddef.h
+++ b/include/stddef.h
@@ -17,7 +17,7 @@ typedef union { long long __ll; long double __ld; } max_align_t;
 typedef signed char int8_t;
 typedef signed short int int16_t;
 typedef signed int int32_t;
-#ifdef __LP64__
+#if defined(__LP64__) && !defined(__APPLE__)
 typedef signed long int int64_t;
 #else
 typedef signed long long int int64_t;
@@ -25,7 +25,7 @@ typedef signed long long int int64_t;
 typedef unsigned char uint8_t;
 typedef unsigned short int uint16_t;
 typedef unsigned int uint32_t;
-#ifdef __LP64__
+#if defined(__LP64__) && !defined(__APPLE__)
 typedef unsigned long int uint64_t;
 #else
 typedef unsigned long long int uint64_t;
@@ -36,6 +36,7 @@ typedef unsigned long long int uint64_t;
 #define NULL ((void*)0)
 #endif
 
+#undef offsetof
 #define offsetof(type, field) ((size_t)&((type *)0)->field)
 
 void *alloca(size_t size);
diff --git a/lib/alloca86_64.S b/lib/alloca86_64.S
index a4aa173..bb03233 100644
--- a/lib/alloca86_64.S
+++ b/lib/alloca86_64.S
@@ -1,6 +1,9 @@
 /* ---------------------------------------------- */
 /* alloca86_64.S */
 
+#ifdef __APPLE__
+#define alloca _alloca
+#endif
 .globl alloca
 
 alloca:
diff --git a/libtcc.c b/libtcc.c
index 256dfb6..8f95ace 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -943,6 +943,7 @@ LIBTCCAPI TCCState *tcc_new(void)
     /* emulate APPLE-GCC to make libc's headerfiles compile: */
     tcc_define_symbol(s, "__APPLE__", "1");
     tcc_define_symbol(s, "__GNUC__", "4");   /* darwin emits warning on GCC<4 */
+    tcc_define_symbol(s, "__APPLE_CC__", "1"); /* for <TargetConditionals.h> */
 
     /* avoids usage of GCC/clang specific builtins in libc-headerfiles: */
     tcc_define_symbol(s, "__FINITE_MATH_ONLY__", "1");