diff --git a/compiler/fir/tree/build.gradle.kts b/compiler/fir/tree/build.gradle.kts
index dc4817df873..f847ce42d71 100644
--- a/compiler/fir/tree/build.gradle.kts
+++ b/compiler/fir/tree/build.gradle.kts
@@ -39,7 +39,7 @@ val generateVisitors by tasks.creating(NoDebugJavaExec::class) {
     }
 
     inputs.files(allSourceFiles)
-    outputs.files(output)
+    outputs.dirs(output)
 
     classpath = generatorClasspath
     args(generationRoot, output)