diff --git a/README.md b/README.md
index 265fa6b..ebf128f 100644
--- a/README.md
+++ b/README.md
@@ -160,7 +160,8 @@ Wrapped headers and replaced functions are:
   </tr>
   <tr>
     <td><code>TargetConditionals.h</code></td>
-    <td>Adds definition for <code>TARGET_OS_SIMULATOR</code> if needed.</td>
+    <td>Adds definition for <code>TARGET_OS_SIMULATOR</code> and 
+        <code>TARGET_OS_OSX</code> if needed.</td>
     <td>OSX10.10</td>
   </tr>
 </table>
diff --git a/include/TargetConditionals.h b/include/TargetConditionals.h
index 9b4af1e..d90bfc8 100644
--- a/include/TargetConditionals.h
+++ b/include/TargetConditionals.h
@@ -24,3 +24,7 @@
 #ifndef TARGET_OS_SIMULATOR
 #  define TARGET_OS_SIMULATOR         0
 #endif
+
+#ifndef TARGET_OS_OSX
+#  define TARGET_OS_OSX               1
+#endif