diff --git a/src/lib/client/ServerProxy.cpp b/src/lib/client/ServerProxy.cpp
index c50e44d9..0a995846 100644
--- a/src/lib/client/ServerProxy.cpp
+++ b/src/lib/client/ServerProxy.cpp
@@ -546,6 +546,7 @@ ServerProxy::setClipboard()
 {
 	// parse
 	static String dataCached;
+	static size_t expectedSize;
 	ClipboardID id;
 	UInt32 seqNum;
 	size_t mark = 0;
@@ -553,7 +554,7 @@ ServerProxy::setClipboard()
 	ProtocolUtil::readf(m_stream, kMsgDClipboard + 4, &id, &seqNum, &mark, &data);
 
 	if (mark == kDataStart) {
-		//TODO: validate size
+		expectedSize = synergy::string::stringToSizeType(data);
 		LOG((CLOG_DEBUG "start receiving clipboard data"));
 		dataCached.clear();
 	}
@@ -562,14 +563,21 @@ ServerProxy::setClipboard()
 	}
 	else if (mark == kDataEnd) {
 		LOG((CLOG_DEBUG "received clipboard %d size=%d", id, dataCached.size()));
+
 		// validate
 		if (id >= kClipboardEnd) {
 			return;
 		}
+		else if (expectedSize != dataCached.size()) {
+			LOG((CLOG_ERR "corrupted clipboard data, expected size=%d actual size=%d", expectedSize, dataCached.size()));
+			return;
+		}
+
 		// forward
 		Clipboard clipboard;
 		clipboard.unmarshall(dataCached, 0);
 		m_client->setClipboard(id, &clipboard);
+		expectedSize = 0;
 	}
 }