diff --git a/vncviewer/UserDialog.cxx b/vncviewer/UserDialog.cxx
index 0ac5009..0c2559f 100644
--- a/vncviewer/UserDialog.cxx
+++ b/vncviewer/UserDialog.cxx
@@ -65,7 +65,7 @@
     ObfuscatedPasswd obfPwd(256);
     FILE* fp;
 
-    fp = fopen(passwordFileStr.buf, "r");
+    fp = fopen(passwordFileStr.buf, "rb");
     if (!fp)
       throw rfb::Exception(_("Opening password file failed"));