diff --git a/runner/runner.sh b/runner/runner.sh
index a8f0694..6f3eed4 100755
--- a/runner/runner.sh
+++ b/runner/runner.sh
@@ -6,8 +6,8 @@ cd -- "$(dirname -- "$SCRIPT")"
 
 exec \
 	3>&1 \
-	2> >(sed "s/^/[ERR] /" >&3) \
-	 > >(sed "s/^/[INF] /" >&3)
+	2> >(sed -u "s/^/[ERR] /" >&3) \
+	 > >(sed -u "s/^/[INF] /" >&3)
 
 _CISH_STARTED=false
 function _cish_on_command() {