diff --git a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
index b6bd1e73682..f4b6d6766b9 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
@@ -936,7 +936,7 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
         }
         DataFlowInfo dataFlowInfo = baseTypeInfo.getDataFlowInfo();
         if (isKnownToBeNotNull(baseExpression, context) && !baseType.isError()) {
-            context.trace.report(UNNECESSARY_NOT_NULL_ASSERTION.on(operationSign, baseType));
+            context.trace.report(UNNECESSARY_NOT_NULL_ASSERTION.on(operationSign, TypeUtils.makeNotNullable(baseType)));
         }
         else {
             DataFlowValue value = createDataFlowValue(baseExpression, baseType, context);