diff --git a/idea/idea-test-framework/test/org/jetbrains/kotlin/idea/test/KotlinLightCodeInsightFixtureTestCase.kt b/idea/idea-test-framework/test/org/jetbrains/kotlin/idea/test/KotlinLightCodeInsightFixtureTestCase.kt
index f6999a1b321..f4861475a48 100644
--- a/idea/idea-test-framework/test/org/jetbrains/kotlin/idea/test/KotlinLightCodeInsightFixtureTestCase.kt
+++ b/idea/idea-test-framework/test/org/jetbrains/kotlin/idea/test/KotlinLightCodeInsightFixtureTestCase.kt
@@ -40,6 +40,7 @@ import org.jetbrains.kotlin.idea.compiler.configuration.KotlinCompilerSettings
 import org.jetbrains.kotlin.idea.facet.KotlinFacet
 import org.jetbrains.kotlin.idea.facet.configureFacet
 import org.jetbrains.kotlin.idea.facet.getOrCreateFacet
+import org.jetbrains.kotlin.idea.inspections.UnusedSymbolInspection
 import org.jetbrains.kotlin.idea.test.CompilerTestDirectives.COMPILER_ARGUMENTS_DIRECTIVE
 import org.jetbrains.kotlin.idea.test.CompilerTestDirectives.JVM_TARGET_DIRECTIVE
 import org.jetbrains.kotlin.idea.test.CompilerTestDirectives.LANGUAGE_VERSION_DIRECTIVE
@@ -63,6 +64,12 @@ abstract class KotlinLightCodeInsightFixtureTestCase : KotlinLightCodeInsightFix
 
     override fun setUp() {
         super.setUp()
+        // We do it here to avoid possible initialization problems
+        // UnusedSymbolInspection() calls IDEA UnusedDeclarationInspection() in static initializer,
+        // which in turn registers some extensions provoking "modifications aren't allowed during highlighting"
+        // when done lazily
+        UnusedSymbolInspection()
+
         (StartupManager.getInstance(project) as StartupManagerImpl).runPostStartupActivities()
         VfsRootAccess.allowRootAccess(KotlinTestUtils.getHomeDirectory())