diff --git a/graphlet_utils.cpp b/graphlet_utils.cpp
index f7c59c9..e3aa190 100755
--- a/graphlet_utils.cpp
+++ b/graphlet_utils.cpp
@@ -39,7 +39,7 @@ bool fexists(const char *filename) {
 #ifdef WIN32
     return ifile!=0;
 #else
-    return ifile;
+    return (bool)ifile;
 #endif
 }