diff --git a/.gitmodules b/.gitmodules
index fef1eaa..1c1686b 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -7,3 +7,6 @@
 [submodule "vendor/github.com/bitly/go-hostpool"]
 	path = vendor/github.com/bitly/go-hostpool
 	url = https://github.com/bitly/go-hostpool
+[submodule "vendor/github.com/bmizerany/assert"]
+	path = vendor/github.com/bmizerany/assert
+	url = https://github.com/bmizerany/assert
diff --git a/raw_socket_listener/listener.go b/raw_socket_listener/listener.go
index fc2be20..a4c88fd 100644
--- a/raw_socket_listener/listener.go
+++ b/raw_socket_listener/listener.go
@@ -441,7 +441,7 @@ func (t *Listener) readPcap() {
 					}
 
 					// Invalid length
-					if ihl * 4 > ipLength {
+					if int(ihl * 4) > ipLength {
 						continue
 					}