diff --git a/utils/launch.sh b/utils/launch.sh
index af350b0a..36119541 100755
--- a/utils/launch.sh
+++ b/utils/launch.sh
@@ -69,7 +69,7 @@ done
 which netstat >/dev/null 2>&1 \
     || die "Must have netstat installed"
 
-netstat -ltn | grep -qs "${PORT} .*LISTEN" \
+netstat -ltn | grep -qs ":${PORT} .*LISTEN" \
     && die "Port ${PORT} in use. Try --listen PORT"
 
 trap "cleanup" TERM QUIT INT EXIT