diff --git a/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/KotlinJvmCheckerProvider.kt b/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/KotlinJvmCheckerProvider.kt
index a2088456c69..0853a822abc 100644
--- a/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/KotlinJvmCheckerProvider.kt
+++ b/compiler/frontend.java/src/org/jetbrains/kotlin/load/kotlin/KotlinJvmCheckerProvider.kt
@@ -217,12 +217,18 @@ private fun checkTypeParameterDescriptorsAreNotReified(
 public class JavaNullabilityWarningsChecker : AdditionalTypeChecker {
     private fun JetType.mayBeNull(): NullabilityInformationSource? {
         if (!isError() && !isFlexible() && TypeUtils.isNullableType(this)) return NullabilityInformationSource.KOTLIN
+
+        if (isFlexible() && TypeUtils.isNullableType(flexibility().lowerBound)) return NullabilityInformationSource.KOTLIN
+
         if (getAnnotations().isMarkedNullable()) return NullabilityInformationSource.JAVA
         return null
     }
 
     private fun JetType.mustNotBeNull(): NullabilityInformationSource? {
         if (!isError() && !isFlexible() && !TypeUtils.isNullableType(this)) return NullabilityInformationSource.KOTLIN
+
+        if (isFlexible() && !TypeUtils.isNullableType(flexibility().upperBound)) return NullabilityInformationSource.KOTLIN
+
         if (!isMarkedNullable() && getAnnotations().isMarkedNotNull()) return NullabilityInformationSource.JAVA
         return null
     }