diff --git a/src/typedefs.h b/src/typedefs.h
index b21d9c756a..d6d4015533 100644
--- a/src/typedefs.h
+++ b/src/typedefs.h
@@ -9,17 +9,22 @@
  */
 
 // This file contains platform-specific typedefs and defines.
+// Much of it is derived from Chromium's build/build_config.h.
 
 #ifndef WEBRTC_TYPEDEFS_H_
 #define WEBRTC_TYPEDEFS_H_
 
 // Reserved words definitions
-// TODO(andrew): Look at removing these.
-#define WEBRTC_EXTERN extern
+// TODO(andrew): Remove this.
 #define G_CONST const
-#define WEBRTC_INLINE extern __inline
 
-// Derived from Chromium's build/build_config.h
+// For access to standard POSIXish features, use WEBRTC_POSIX instead of a
+// more specific macro.
+#if defined(WEBRTC_MAC) || defined(WEBRTC_LINUX) || \
+    defined(WEBRTC_ANDROID)
+#define WEBRTC_POSIX
+#endif
+
 // Processor architecture detection.  For more info on what's defined, see:
 //   http://msdn.microsoft.com/en-us/library/b0084kay.aspx
 //   http://www.agner.org/optimize/calling_conventions.pdf