diff --git a/src/coreclr/inc/check.inl b/src/coreclr/inc/check.inl
index 070278af8f9be6de4493d78df2bb02ab16a0b339..9296c48f7a7a3d25b23c65e3df1c93f93c454c89 100644
--- a/src/coreclr/inc/check.inl
+++ b/src/coreclr/inc/check.inl
@@ -220,14 +220,14 @@ inline CHECK CheckOverflow(const void *address, UINT64 offset)
     CHECK_OK;
 }
 
-#if defined(HOST_UNIX) && defined(HOST_64BIT)
+#ifdef __APPLE__
 inline CHECK CheckOverflow(const void *address, SIZE_T offset)
 {
     CHECK((UINT64) address + offset >= (UINT64) address);
 
     CHECK_OK;
 }
-#endif // HOST_UNIX && HOST_BIT64
+#endif // __APPLE__
 
 inline CHECK CheckUnderflow(UINT value1, UINT value2)
 {
diff --git a/src/coreclr/inc/clrtypes.h b/src/coreclr/inc/clrtypes.h
index 6ab68eb03581fc36fe7c2a7126e3d59f2596a839..19e9720b34d90bcc52f36aff17cb21840a35773c 100644
--- a/src/coreclr/inc/clrtypes.h
+++ b/src/coreclr/inc/clrtypes.h
@@ -338,14 +338,14 @@ inline UINT64 AlignUp(UINT64 value, UINT alignment)
     return (value+alignment-1)&~(UINT64)(alignment-1);
 }
 
-#if defined(HOST_UNIX) && defined(HOST_64BIT)
+#ifdef __APPLE__
 inline SIZE_T AlignUp(SIZE_T value, UINT alignment)
 {
     STATIC_CONTRACT_LEAF;
     STATIC_CONTRACT_SUPPORTS_DAC;
     return (value+alignment-1)&~(SIZE_T)(alignment-1);
 }
-#endif // HOST_UNIX && HOST_BIT64
+#endif // __APPLE__
 
 inline UINT AlignDown(UINT value, UINT alignment)
 {
@@ -390,13 +390,13 @@ inline UINT AlignmentPad(UINT64 value, UINT alignment)
     return (UINT) (AlignUp(value, alignment) - value);
 }
 
-#if defined(HOST_UNIX) && defined(HOST_64BIT)
+#ifdef __APPLE__
 inline UINT AlignmentPad(SIZE_T value, UINT alignment)
 {
     STATIC_CONTRACT_WRAPPER;
     return (UINT) (AlignUp(value, alignment) - value);
 }
-#endif // HOST_UNIX && HOST_BIT64
+#endif // __APPLE__
 
 inline UINT AlignmentTrim(UINT value, UINT alignment)
 {
@@ -423,13 +423,13 @@ inline UINT AlignmentTrim(UINT64 value, UINT alignment)
     return ((UINT)value)&(alignment-1);
 }
 
-#if defined(HOST_UNIX) && defined(HOST_64BIT)
+#ifdef __APPLE__
 inline UINT AlignmentTrim(SIZE_T value, UINT alignment)
 {
     STATIC_CONTRACT_LEAF;
     STATIC_CONTRACT_SUPPORTS_DAC;
     return ((UINT)value)&(alignment-1);
 }
-#endif // HOST_UNIX && HOST_BIT64
+#endif // __APPLE__
 
 #endif  // CLRTYPES_H_
diff --git a/src/coreclr/jit/compiler.hpp b/src/coreclr/jit/compiler.hpp
index ecce3c1aa0272bdce2af23a67b02e9ebad8720f9..274514bbf9831f3ea548b110308fcfc56a937907 100644
--- a/src/coreclr/jit/compiler.hpp
+++ b/src/coreclr/jit/compiler.hpp
@@ -233,12 +233,12 @@ inline unsigned genLog2(unsigned __int64 value)
 #endif
 }
 
-#if defined(HOST_UNIX) && defined(HOST_64BIT)
+#ifdef __APPLE__
 inline unsigned genLog2(size_t value)
 {
     return genLog2((unsigned __int64)value);
 }
-#endif // HOST_UNIX && HOST_BIT64
+#endif // __APPLE__
 
 /*****************************************************************************
  *
diff --git a/src/coreclr/jit/jit.h b/src/coreclr/jit/jit.h
index 8d8eedd914bcf308b9aa2403914a5093a5ac072e..984ef0f12e34ac36896b3b9a007d10580c8dbafa 100644
--- a/src/coreclr/jit/jit.h
+++ b/src/coreclr/jit/jit.h
@@ -634,12 +634,12 @@ inline size_t unsigned_abs(ssize_t x)
     return ((size_t)abs((__int64)x));
 }
 
-#ifdef HOST_UNIX
+#ifdef __APPLE__
 inline size_t unsigned_abs(__int64 x)
 {
     return ((size_t)abs(x));
 }
-#endif // HOST_UNIX
+#endif // __APPLE__
 #endif // TARGET_64BIT
 
 /*****************************************************************************/
diff --git a/src/coreclr/pal/inc/pal.h b/src/coreclr/pal/inc/pal.h
index 48bc4b42236619b3411f75270e2be715fb8c4522..6937147dd3b2c59866760b1b4d895732d1f06b57 100644
--- a/src/coreclr/pal/inc/pal.h
+++ b/src/coreclr/pal/inc/pal.h
@@ -4321,7 +4321,7 @@ inline __int64 abs(__int64 _X) {
     return llabs(_X);
 }
 
-#ifdef HOST_64BIT
+#ifdef __APPLE__
 inline __int64 abs(SSIZE_T _X) {
     return llabs((__int64)_X);
 }
diff --git a/src/coreclr/pal/inc/pal_mstypes.h b/src/coreclr/pal/inc/pal_mstypes.h
index ddeb135f2cce10e04f23372d198133173ddf6b4b..1eee6b2bbbd24534f51141927af7f37908d506e6 100644
--- a/src/coreclr/pal/inc/pal_mstypes.h
+++ b/src/coreclr/pal/inc/pal_mstypes.h
@@ -195,7 +195,11 @@ extern "C" {
 // they must be either signed or unsigned) and we want to be able to use
 // __int64 as though it were intrinsic
 
+#if defined(HOST_64BIT) && !defined(__APPLE__)
+#define __int64     long
+#else // HOST_64BIT && !__APPLE__
 #define __int64     long long
+#endif // HOST_64BIT && !__APPLE__
 #define __int32     int
 #define __int16     short int
 #define __int8      char        // assumes char is signed