diff --git a/worker/agent.go b/worker/agent.go
index 3367ad3..ad72690 100644
--- a/worker/agent.go
+++ b/worker/agent.go
@@ -86,7 +86,8 @@ func (a *agent) work() {
 		if len(leftdata) > 0 { // some data left for processing
 			data = append(leftdata, data...)
 		}
-		if len(data) < minPacketLength { // not enough data
+		length := len(data) - minPacketLength
+		if length < 0 || length < int(binary.BigEndian.Uint32(data[8:12])) {
 			leftdata = data
 			continue
 		}
diff --git a/worker/inpack.go b/worker/inpack.go
index fc4717a..c777b80 100644
--- a/worker/inpack.go
+++ b/worker/inpack.go
@@ -86,6 +86,8 @@ func (inpack *inPack) UpdateStatus(numerator, denominator int) {
 
 // Decode job from byte slice
 func decodeInPack(data []byte) (inpack *inPack, l int, err error) {
+	// The next three checks should be completely unnecessary, as they are checked in
+	// agent.work.
 	if len(data) < minPacketLength { // valid package should not less 12 bytes
 		err = fmt.Errorf("Invalid data: %v", data)
 		return