diff --git a/idea/idea-gradle/src/org/jetbrains/kotlin/idea/scripting/gradle/LastModifiedFiles.kt b/idea/idea-gradle/src/org/jetbrains/kotlin/idea/scripting/gradle/LastModifiedFiles.kt
index 4e3f6c299a3..9dad5b6af53 100644
--- a/idea/idea-gradle/src/org/jetbrains/kotlin/idea/scripting/gradle/LastModifiedFiles.kt
+++ b/idea/idea-gradle/src/org/jetbrains/kotlin/idea/scripting/gradle/LastModifiedFiles.kt
@@ -86,7 +86,7 @@ class LastModifiedFiles(
 
         private fun DataOutput.writeSCF(last: SimultaneouslyChangedFiles) {
             writeLong(last.ts)
-            writeStringList(last.fileIds)
+            writeStringList(last.fileIds.toList())
         }
     }
 }
\ No newline at end of file