diff --git a/graphlet_utils.cpp b/graphlet_utils.cpp
index f7c59c9..a85372f 100755
--- a/graphlet_utils.cpp
+++ b/graphlet_utils.cpp
@@ -37,9 +37,9 @@ using namespace std;
 bool fexists(const char *filename) {
     ifstream ifile(filename);
 #ifdef WIN32
-    return ifile!=0;
+    return (bool) ifile!=0;
 #else
-    return ifile;
+    return (bool) ifile;
 #endif
 }