diff --git a/modules/osx/init.zsh b/modules/osx/init.zsh
index 83c4e67..953cba7 100644
--- a/modules/osx/init.zsh
+++ b/modules/osx/init.zsh
@@ -5,6 +5,11 @@
 #   Sorin Ionescu <sorin.ionescu@gmail.com>
 #
 
+# This module is for Mac OS X only.
+if [[ "$OSTYPE" != darwin* ]]; then
+  return 1
+fi
+
 # Change directory to the current Finder directory.
 alias cdf='cd "$(pfd)"'