diff --git a/scrap2rtf/src/common_func.cpp b/scrap2rtf/src/common_func.cpp
index 07f96bf..9508460 100644
--- a/scrap2rtf/src/common_func.cpp
+++ b/scrap2rtf/src/common_func.cpp
@@ -17,6 +17,7 @@
    Andrey Ivnitsky <ivnitsky.a@gmail.com> */
 
 #include "common_func.h"
+#include <unistd.h>
 
 /* Extract file extension */
 const string ExtractFileExt(const string szFileName)