diff --git a/cc/util.go b/cc/util.go
index 92a32bc..aaf0f71 100644
--- a/cc/util.go
+++ b/cc/util.go
@@ -80,6 +80,7 @@
 		coverage:       in.Coverage,
 		tidy:           in.Tidy,
 		sAbiDump:       in.SAbiDump,
+		protoRoot:      in.ProtoRoot,
 
 		systemIncludeFlags: strings.Join(in.SystemIncludeFlags, " "),