diff --git a/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.kt b/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.kt
new file mode 100644
index 00000000000..ebf365b3cd8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.kt
@@ -0,0 +1,20 @@
+// !CHECK_TYPE
+// FILE: A.java
+public class A {
+    public static String foo() {
+        return "";
+    }
+}
+
+// FILE: b.kt
+fun <T: Any> exclExcl(t: T?): T = t!!
+
+fun test11() {
+    // not 'String!'
+    exclExcl(A.foo()) checkType { it : _<String> }
+    exclExcl(A.foo()) checkType { <!TYPE_MISMATCH!>it<!> : _<String?> }
+
+    // not 'String!'
+    A.foo()!! checkType { it : _<String> }
+    A.foo()!! checkType { <!TYPE_MISMATCH!>it<!> : _<String?> }
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.txt b/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.txt
new file mode 100644
index 00000000000..f0e28eae292
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.txt
@@ -0,0 +1,14 @@
+package
+
+internal fun </*0*/ T : kotlin.Any> exclExcl(/*0*/ t: T?): T
+internal fun test11(): kotlin.Unit
+
+public open class A {
+    public constructor A()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public open fun foo(): kotlin.String!
+}
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java
index ee0a137c7e9..ce165337a55 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java
@@ -2022,6 +2022,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("typeInferenceForExclExcl.kt")
+            public void testTypeInferenceForExclExcl() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlStructures/typeInferenceForExclExcl.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("valVarCatchParameter.kt")
             public void testValVarCatchParameter() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlStructures/valVarCatchParameter.kt");
diff --git a/core/descriptors/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt b/core/descriptors/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt
index 1263450de12..a879972d631 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/resolve/calls/inference/ConstraintSystemImpl.kt
@@ -333,18 +333,20 @@ public class ConstraintSystemImpl : ConstraintSystem {
 
         val typeBounds = getTypeBounds(parameterType)
 
-        if (!parameterType.isMarkedNullable() || !newConstrainingType.isMarkedNullable()) {
+        if (!parameterType.isMarkedNullable() || !TypeUtils.isNullableType(newConstrainingType)) {
             typeBounds.addBound(boundKind, newConstrainingType, constraintPosition)
             return
         }
         // For parameter type T:
         // constraint T? =  Int? should transform to T >: Int and T <: Int?
-        // constraint T? >: Int? should transform to T >: Int
+        // constraint T? = Int! should transform to T >: Int and T <: Int!
+
+        // constraints T? >: Int?; T? >: Int! should transform to T >: Int
         val notNullConstrainingType = TypeUtils.makeNotNullable(newConstrainingType)
         if (boundKind == EXACT_BOUND || boundKind == LOWER_BOUND) {
             typeBounds.addBound(LOWER_BOUND, notNullConstrainingType, constraintPosition)
         }
-        // constraint T? <: Int? should transform to T <: Int?
+        // constraints T? <: Int?; T? <: Int! should transform to T <: Int?; T <: Int! correspondingly
         if (boundKind == EXACT_BOUND || boundKind == UPPER_BOUND) {
             typeBounds.addBound(UPPER_BOUND, newConstrainingType, constraintPosition)
         }