diff --git a/README.md b/README.md
index 4c5a9b27815..d9635d44a6d 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@ Evented I/O for V8 javascript.
 
 ### To build:
 
-Unix/Macintosh:
+Unix/Macintosh (requires python >= 2.5.2):
 
     ./configure
     make