diff --git a/java/builder.go b/java/builder.go
index 5aea1cb..b8f8351 100644
--- a/java/builder.go
+++ b/java/builder.go
@@ -169,6 +169,7 @@
 	protoFlags       []string
 	protoOutTypeFlag string // The flag itself: --java_out
 	protoOutParams   string // Parameters to that flag: --java_out=$protoOutParams:$outDir
+	protoRoot        bool
 }
 
 func TransformKotlinToClasses(ctx android.ModuleContext, outputFile android.WritablePath,