diff --git a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerFirTestdataTestGenerated.java b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerFirTestdataTestGenerated.java
index 61cbf15ddd9..044aa9e1f4f 100644
--- a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerFirTestdataTestGenerated.java
+++ b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerFirTestdataTestGenerated.java
@@ -4835,6 +4835,12 @@ public class DiagnosisCompilerFirTestdataTestGenerated extends AbstractDiagnosis
                 KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/types"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
             }
 
+            @Test
+            @TestMetadata("bareWithDnnArg.kt")
+            public void testBareWithDnnArg() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt");
+            }
+
             @Test
             @TestMetadata("bareWithFlexibleArg.kt")
             public void testBareWithFlexibleArg() throws Exception {
diff --git a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java
index 5c61d155333..245c4f6a55a 100644
--- a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java
+++ b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java
@@ -489,6 +489,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
             runTest("compiler/testData/diagnostics/tests/kt55733.kt");
         }
 
+        @Test
+        @TestMetadata("kt56612.kt")
+        public void testKt56612() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/kt56612.kt");
+        }
+
         @Test
         @TestMetadata("kt56665.kt")
         public void testKt56665() throws Exception {
diff --git a/compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java b/compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java
index fcddcfa9e36..c64365e3efe 100644
--- a/compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java
+++ b/compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java
@@ -4307,6 +4307,11 @@ public class LazyBodyIsNotTouchedTilContractsPhaseTestGenerated extends Abstract
             KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/types"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
         }
 
+        @TestMetadata("bareWithDnnArg.kt")
+        public void testBareWithDnnArg() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt");
+        }
+
         @TestMetadata("bareWithFlexibleArg.kt")
         public void testBareWithFlexibleArg() throws Exception {
             runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithFlexibleArg.kt");
diff --git a/compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.fir.txt b/compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.fir.txt
new file mode 100644
index 00000000000..6cd02900eb9
--- /dev/null
+++ b/compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.fir.txt
@@ -0,0 +1,16 @@
+FILE: main.kt
+    public abstract interface KotlinCancellablePromise<E> : R|Promise<E>| {
+    }
+    public final class D<T> : R|kotlin/Any| {
+        public constructor<T>(): R|D<T>| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final fun foo(x: R|Promise<T & Any>|): R|kotlin/Unit| {
+            this@R|/D|.R|/D.bar|((R|<local>/x| as R|KotlinCancellablePromise<T & Any>|))
+        }
+
+        public final fun bar(x: R|KotlinCancellablePromise<T & Any>|): R|kotlin/Unit| {
+        }
+
+    }
diff --git a/compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt b/compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt
new file mode 100644
index 00000000000..593469f7a05
--- /dev/null
+++ b/compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt
@@ -0,0 +1,17 @@
+// FIR_IDENTICAL
+// SKIP_TXT
+
+// FILE: Promise.java
+public interface Promise<T> {}
+
+// FILE: main.kt
+
+interface KotlinCancellablePromise<E> : Promise<E>
+
+class D<T> {
+    fun foo(x: Promise<T & Any>) {
+        bar(x as KotlinCancellablePromise)
+    }
+
+    fun bar(x: KotlinCancellablePromise<T & Any>) {}
+}
diff --git a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticTestGenerated.java b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticTestGenerated.java
index 9fa693f643c..04a3ec2a06a 100644
--- a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticTestGenerated.java
+++ b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticTestGenerated.java
@@ -4835,6 +4835,12 @@ public class FirDiagnosticTestGenerated extends AbstractFirDiagnosticTest {
                 KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/types"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
             }
 
+            @Test
+            @TestMetadata("bareWithDnnArg.kt")
+            public void testBareWithDnnArg() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt");
+            }
+
             @Test
             @TestMetadata("bareWithFlexibleArg.kt")
             public void testBareWithFlexibleArg() throws Exception {
diff --git a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticsWithLightTreeTestGenerated.java b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticsWithLightTreeTestGenerated.java
index 97b09115f88..c3f80db8f47 100644
--- a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticsWithLightTreeTestGenerated.java
+++ b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirDiagnosticsWithLightTreeTestGenerated.java
@@ -4835,6 +4835,12 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
                 KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/types"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
             }
 
+            @Test
+            @TestMetadata("bareWithDnnArg.kt")
+            public void testBareWithDnnArg() throws Exception {
+                runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithDnnArg.kt");
+            }
+
             @Test
             @TestMetadata("bareWithFlexibleArg.kt")
             public void testBareWithFlexibleArg() throws Exception {
diff --git a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java
index 8a0b93dce5d..c24c492b24d 100644
--- a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java
+++ b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java
@@ -489,6 +489,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
             runTest("compiler/testData/diagnostics/tests/kt55733.kt");
         }
 
+        @Test
+        @TestMetadata("kt56612.kt")
+        public void testKt56612() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/kt56612.kt");
+        }
+
         @Test
         @TestMetadata("kt56665.kt")
         public void testKt56665() throws Exception {
diff --git a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java
index 0f5e52f6578..8a9850d9bea 100644
--- a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java
+++ b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java
@@ -489,6 +489,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
             runTest("compiler/testData/diagnostics/tests/kt55733.kt");
         }
 
+        @Test
+        @TestMetadata("kt56612.kt")
+        public void testKt56612() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/kt56612.kt");
+        }
+
         @Test
         @TestMetadata("kt56665.kt")
         public void testKt56665() throws Exception {
diff --git a/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUnification.kt b/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUnification.kt
index 790a627db90..820479de5fc 100644
--- a/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUnification.kt
+++ b/compiler/fir/providers/src/org/jetbrains/kotlin/fir/types/TypeUnification.kt
@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.types
 
 import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.resolve.fullyExpandedType
 import org.jetbrains.kotlin.fir.symbols.impl.FirTypeParameterSymbol
 import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.types.model.KotlinTypeMarker
@@ -22,8 +23,8 @@ fun FirSession.doUnify(
     targetTypeParameters: Set<FirTypeParameterSymbol>,
     result: MutableMap<FirTypeParameterSymbol, ConeTypeProjection>,
 ): Boolean {
-    val originalType = originalTypeProjection.type?.lowerBoundIfFlexible()
-    val typeWithParameters = typeWithParametersProjection.type
+    val originalType = originalTypeProjection.type?.lowerBoundIfFlexible()?.fullyExpandedType(this)
+    val typeWithParameters = typeWithParametersProjection.type?.lowerBoundIfFlexible()?.fullyExpandedType(this)
 
     if (originalType is ConeIntersectionType) {
         val intersectionResult = mutableMapOf<FirTypeParameterSymbol, ConeTypeProjection>()
@@ -68,14 +69,6 @@ fun FirSession.doUnify(
         return true
     }
 
-    if (typeWithParameters is ConeFlexibleType) {
-        return doUnify(
-            originalTypeProjection,
-            typeWithParametersProjection.replaceType(typeWithParameters.lowerBound),
-            targetTypeParameters, result,
-        )
-    }
-
     if (typeWithParameters is ConeDefinitelyNotNullType) {
         return doUnify(
             originalTypeProjection,
diff --git a/compiler/testData/diagnostics/tests/kt56612.kt b/compiler/testData/diagnostics/tests/kt56612.kt
new file mode 100644
index 00000000000..6ab9481ba9c
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/kt56612.kt
@@ -0,0 +1,29 @@
+// FIR_IDENTICAL
+
+interface FlameGraphModel<T>
+
+internal typealias CallUsageNode = CallTreeNode<BaseCallStackElement>
+
+interface CallTreeNode<out T : Any> : TreeNodeWithParent<CallWithValue<T>>
+
+interface TreeNodeWithParent<out Data>
+
+interface CallWithValue<out T : Any>
+
+abstract class BaseCallStackElement
+
+open class CallUsageNodeFlameGraphModel<Call : Any> : FlameGraphModel<CallTreeNode<Call>>
+
+fun foo(model: FlameGraphModel<CallUsageNode>) {
+    // K1: Ok
+    val afterCast = model as CallUsageNodeFlameGraphModel
+}
+
+internal typealias CallTreeNodeTypealias<K> = CallTreeNode<K>
+
+open class CallUsageNodeFlameGraphModelWithTypealiasedSupertypeArgument<Call : Any> : FlameGraphModel<CallTreeNodeTypealias<Call>>
+
+fun bar(model: FlameGraphModel<CallUsageNode>) {
+    // K1: Ok
+    val afterCast = model as CallUsageNodeFlameGraphModelWithTypealiasedSupertypeArgument
+}
diff --git a/compiler/testData/diagnostics/tests/kt56612.txt b/compiler/testData/diagnostics/tests/kt56612.txt
new file mode 100644
index 00000000000..98cf098f6a8
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/kt56612.txt
@@ -0,0 +1,51 @@
+package
+
+public fun bar(/*0*/ model: FlameGraphModel<CallUsageNode /* = CallTreeNode<BaseCallStackElement> */>): kotlin.Unit
+public fun foo(/*0*/ model: FlameGraphModel<CallUsageNode /* = CallTreeNode<BaseCallStackElement> */>): kotlin.Unit
+
+public abstract class BaseCallStackElement {
+    public constructor BaseCallStackElement()
+    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
+}
+
+public interface CallTreeNode</*0*/ out T : kotlin.Any> : TreeNodeWithParent<CallWithValue<T>> {
+    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
+}
+
+public open class CallUsageNodeFlameGraphModel</*0*/ Call : kotlin.Any> : FlameGraphModel<CallTreeNode<Call>> {
+    public constructor CallUsageNodeFlameGraphModel</*0*/ Call : kotlin.Any>()
+    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
+}
+
+public open class CallUsageNodeFlameGraphModelWithTypealiasedSupertypeArgument</*0*/ Call : kotlin.Any> : FlameGraphModel<CallTreeNodeTypealias<Call> /* = CallTreeNode<Call> */> {
+    public constructor CallUsageNodeFlameGraphModelWithTypealiasedSupertypeArgument</*0*/ Call : kotlin.Any>()
+    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
+}
+
+public interface CallWithValue</*0*/ out T : kotlin.Any> {
+    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
+}
+
+public interface FlameGraphModel</*0*/ T> {
+    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
+}
+
+public interface TreeNodeWithParent</*0*/ out Data> {
+    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
+}
+internal typealias CallTreeNodeTypealias</*0*/ K> = CallTreeNode<K>
+internal typealias CallUsageNode = CallTreeNode<BaseCallStackElement>
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java
index dc0c1e42cfd..d15a367f4ae 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java
@@ -489,6 +489,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
             runTest("compiler/testData/diagnostics/tests/kt55733.kt");
         }
 
+        @Test
+        @TestMetadata("kt56612.kt")
+        public void testKt56612() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/kt56612.kt");
+        }
+
         @Test
         @TestMetadata("kt56665.kt")
         public void testKt56665() throws Exception {