diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt
index 08b90f7e203..73ceb2334cf 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt
@@ -157,7 +157,7 @@ object FirOptInUsageBaseChecker {
             }
             if (fir !is FirConstructor) {
                 // Without coneTypeSafe v fails in MT test (FirRenderer.kt)
-                fir.returnTypeRef.coneType.addExperimentalities(context, result, visited)
+                fir.returnTypeRef.coneTypeSafe<ConeKotlinType>().addExperimentalities(context, result, visited)
                 fir.receiverTypeRef?.coneType.addExperimentalities(context, result, visited)
                 if (fir is FirSimpleFunction) {
                     fir.valueParameters.forEach {