diff --git a/External/Tools/Notepad2.exe b/External/Tools/Notepad2.exe
deleted file mode 100644
index 2a29d3a42a..0000000000
Binary files a/External/Tools/Notepad2.exe and /dev/null differ
diff --git a/Languages/IronPython/IronPython/Runtime/PythonFile.cs b/Languages/IronPython/IronPython/Runtime/PythonFile.cs
index 167fef355b..e8f58fb792 100644
--- a/Languages/IronPython/IronPython/Runtime/PythonFile.cs
+++ b/Languages/IronPython/IronPython/Runtime/PythonFile.cs
@@ -1217,23 +1217,24 @@ private static void TranslateAndValidateMode(string mode, out FileMode fmode, ou
                     mode = "r+";
                 } else if (mode[0] == 'w' || mode[0] == 'a') {
                     throw PythonOps.ValueError("universal newline mode can only be used with modes starting with 'r'");
-                } else {
+                } else if (mode[0] != 'r') {
                     mode = "r" + mode;
                 }
             }
 
-            // process read/write/append
+            // process read/write/append and remove char from mode
             seekEnd = false;
             switch (mode[0]) {
-                case 'r': fmode = FileMode.Open; break;
-                case 'w': fmode = FileMode.Create; break;
-                case 'a': fmode = FileMode.Append; break;
+                case 'r': fmode = FileMode.Open; mode = mode.Remove(0, 1); break;
+                case 'w': fmode = FileMode.Create; mode = mode.Remove(0, 1); break;
+                case 'a': fmode = FileMode.Append; mode = mode.Remove(0, 1); break;
                 default:
                     throw PythonOps.ValueError("mode string must begin with one of 'r', 'w', 'a' or 'U', not '{0}'", inMode);
             }
 
             // process +
             if (mode.IndexOf('+') != -1) {
+                mode = mode.Remove(mode.IndexOf('+'), 1);
                 faccess = FileAccess.ReadWrite;
                 if (fmode == FileMode.Append) {
                     fmode = FileMode.OpenOrCreate;
@@ -1247,6 +1248,13 @@ private static void TranslateAndValidateMode(string mode, out FileMode fmode, ou
                     default: throw new InvalidOperationException();
                 }
             }
+
+            // Make some additional mode check after processing all valid modes.
+            if (mode.Length > 0) {
+                if (mode[0] != 'U' && mode[0] != 'b' && mode[0] != 't') {
+                    throw PythonOps.ValueError("Invalid mode ('{0}')", inMode);
+                }
+            }
         }
 
         public void __init__(CodeContext/*!*/ context, [NotNull]Stream/*!*/ stream) {