diff --git a/src/osgDB/ReaderWriter.cpp b/src/osgDB/ReaderWriter.cpp
index 8cf48cf17..fa8a26b8e 100644
--- a/src/osgDB/ReaderWriter.cpp
+++ b/src/osgDB/ReaderWriter.cpp
@@ -118,6 +118,13 @@ ReaderWriter::FeatureList ReaderWriter::featureAsString(ReaderWriter::Features f
     return result;
 }
 
+#if defined(WIN32) && !defined(__CYGWIN__)
+    #include <io.h>
+#ifndef F_OK
+    #define F_OK 4
+#endif
+#endif
+
 bool ReaderWriter::fileExists(const std::string& filename, const Options* /*options*/) const
 {
 #ifdef OSG_USE_UTF8_FILENAME