diff --git a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/file/structure/FileStructure.kt b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/file/structure/FileStructure.kt
index 7b8362dfda2..7c3e546bfd8 100644
--- a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/file/structure/FileStructure.kt
+++ b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/file/structure/FileStructure.kt
@@ -59,8 +59,11 @@ internal class FileStructure(
     @OptIn(ExperimentalStdlibApi::class)
     fun getAllDiagnosticsForFile(diagnosticCheckerFilter: DiagnosticCheckerFilter): Collection<FirPsiDiagnostic<*>> {
         val structureElements = getAllStructureElements()
-        return buildSet {
-            collectDiagnosticsFromStructureElements(structureElements, diagnosticCheckerFilter)
+
+        return moduleFileCache.firFileLockProvider.withReadLock(firFile) {
+            buildSet {
+                collectDiagnosticsFromStructureElements(structureElements, diagnosticCheckerFilter)
+            }
         }
     }