diff --git a/runtime/bin/builtin_impl_sources.gypi b/runtime/bin/builtin_impl_sources.gypi
index 9d9d8acb8f5..d62c091be75 100644
--- a/runtime/bin/builtin_impl_sources.gypi
+++ b/runtime/bin/builtin_impl_sources.gypi
@@ -61,5 +61,6 @@
     'utils_linux.cc',
     'utils_macos.cc',
     'utils_win.cc',
+    'utils_win.h',
   ],
 }
diff --git a/runtime/bin/process_win.cc b/runtime/bin/process_win.cc
index d3efd4cc5f6..c83afabdb78 100644
--- a/runtime/bin/process_win.cc
+++ b/runtime/bin/process_win.cc
@@ -13,6 +13,7 @@
 #include "bin/log.h"
 #include "bin/thread.h"
 #include "bin/utils.h"
+#include "bin/utils_win.h"
 
 
 namespace dart {
@@ -305,21 +306,7 @@ static int SetOsErrorMessage(char** os_error_message) {
   int error_code = GetLastError();
   static const int kMaxMessageLength = 256;
   wchar_t message[kMaxMessageLength];
-  DWORD message_size =
-      FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
-                     NULL,
-                     error_code,
-                     MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-                     message,
-                     kMaxMessageLength,
-                     NULL);
-  if (message_size == 0) {
-    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
-      Log::PrintErr("FormatMessage failed %d\n", GetLastError());
-    }
-    _snwprintf(message, kMaxMessageLength, L"OS Error %d", error_code);
-  }
-  message[kMaxMessageLength - 1] = '\0';
+  FormatMessageIntoBuffer(error_code, message, kMaxMessageLength);
   *os_error_message = StringUtils::WideToUtf8(message);
   return error_code;
 }
diff --git a/runtime/bin/utils_win.cc b/runtime/bin/utils_win.cc
index b926dd767de..dab73552daa 100644
--- a/runtime/bin/utils_win.cc
+++ b/runtime/bin/utils_win.cc
@@ -9,15 +9,14 @@
 #include <time.h>  // NOLINT
 
 #include "bin/utils.h"
+#include "bin/utils_win.h"
 #include "bin/log.h"
 
 
 namespace dart {
 namespace bin {
 
-static void FormatMessageIntoBuffer(DWORD code,
-                                    wchar_t* buffer,
-                                    int buffer_length) {
+void FormatMessageIntoBuffer(DWORD code, wchar_t* buffer, int buffer_length) {
   DWORD message_size =
       FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
                      NULL,
@@ -28,11 +27,14 @@ static void FormatMessageIntoBuffer(DWORD code,
                      NULL);
   if (message_size == 0) {
     if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
-      Log::PrintErr("FormatMessage failed %d\n", GetLastError());
+      Log::PrintErr("FormatMessage failed for error code %d (error %d)\n",
+                    code,
+                    GetLastError());
     }
     _snwprintf(buffer, buffer_length, L"OS Error %d", code);
   }
-  buffer[buffer_length - 1] = '\0';
+  // Ensure string termination.
+  buffer[buffer_length - 1] = 0;
 }
 
 
diff --git a/runtime/bin/utils_win.h b/runtime/bin/utils_win.h
new file mode 100644
index 00000000000..a0447604cfe
--- /dev/null
+++ b/runtime/bin/utils_win.h
@@ -0,0 +1,18 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef BIN_UTILS_WIN_H_
+#define BIN_UTILS_WIN_H_
+
+#include "platform/globals.h"
+
+namespace dart {
+namespace bin {
+
+void FormatMessageIntoBuffer(DWORD code, wchar_t* buffer, int buffer_length);
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // BIN_UTILS_WIN_H_