diff --git a/plugins/common/CheckVersionsMessage.cpp b/plugins/common/CheckVersionsMessage.cpp
new file mode 100644
index 0000000..911cf38
--- /dev/null
+++ b/plugins/common/CheckVersionsMessage.cpp
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2008 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+#include "CheckVersionsMessage.h"
+#include "HostChannel.h"
+#include "scoped_ptr/scoped_ptr.h"
+
+CheckVersionsMessage::~CheckVersionsMessage() {
+}
+
+char CheckVersionsMessage::getType() const {
+  return TYPE;
+}
+
+/**
+ * Receive a CheckVersions message from the channel (note that the message
+ * type has already been read).  Caller is responsible for destroying
+ * returned message.  Returns null on error.
+ */
+CheckVersionsMessage* CheckVersionsMessage::receive(HostChannel& channel) {
+  int minVersion;
+  if (!channel.readInt(minVersion)) {
+    // TODO(jat): error handling
+    printf("Failed to read minimum version\n");
+    return 0;
+  }
+  int maxVersion;
+  if (!channel.readInt(maxVersion)) {
+    // TODO(jat): error handling
+    printf("Failed to read maximum version\n");
+    return 0;
+  }
+  std::string hostedHtmlVersion;
+  if (!channel.readString(hostedHtmlVersion)) {
+    // TODO(jat): error handling
+    printf("Failed to read hosted.html version\n");
+    return 0;
+  }
+  return new CheckVersionsMessage(minVersion, maxVersion, hostedHtmlVersion);
+}
+
+/**
+ * Send a fatal error message on the channel.
+ */
+bool CheckVersionsMessage::send(HostChannel& channel, int minVersion,
+    int maxVersion, const std::string& hostedHtmlVersion) {
+  if (!channel.sendByte(TYPE)) return false;
+  if (!channel.sendInt(minVersion)) return false;
+  if (!channel.sendInt(maxVersion)) return false;
+  if (!channel.sendString(hostedHtmlVersion)) return false;
+  return true;
+}