diff --git a/gomilter.go b/gomilter.go
index 68e0d2d..5c8c51a 100644
--- a/gomilter.go
+++ b/gomilter.go
@@ -10,6 +10,8 @@ gomilter.go
 
 */
 
+//+build cgo
+
 package gomilter
 
 /*