diff --git a/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java b/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java
index 4b00197fa3b..5ef41ffb6b0 100644
--- a/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java
+++ b/compiler/fir/fir2ir/tests/org/jetbrains/kotlin/codegen/ir/FirBlackBoxCodegenTestGenerated.java
@@ -9818,6 +9818,11 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }
 
diff --git a/compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt b/compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt
new file mode 100644
index 00000000000..89a291e8423
--- /dev/null
+++ b/compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt
@@ -0,0 +1,31 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+
+import kotlin.reflect.KProperty
+
+class TypeInference {
+    val explicitTypes by providerFun<TypeInference, String>()
+    val withoutTypes: String by providerFun()
+}
+
+class Inv<T>(val x: T)
+
+fun <T, R> T.providerFun() = object : DelegateProvider<T, R>() {
+    override fun provideDelegate(thisRef: T, property: KProperty<*>): Inv<R> {
+        return Inv("OK") as Inv<R>
+    }
+}
+
+operator fun <T> Inv<T>.getValue(thisRef: Any?, property: KProperty<*>): T = x
+
+abstract class DelegateProvider<T, R> {
+    abstract operator fun provideDelegate(
+        thisRef: T,
+        property: KProperty<*>
+    ): Inv<R>
+}
+
+fun box(): String {
+    val t = TypeInference()
+    if (t.explicitTypes != t.withoutTypes) return "fail 1"
+    return t.withoutTypes
+}
\ No newline at end of file
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java
index 7d4deb9400c..26ed564e7ce 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java
@@ -11043,6 +11043,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }
 
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
index b0740b40f59..c5f8dedc0ef 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java
@@ -11043,6 +11043,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }
 
diff --git a/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java
index 3d0153e8f26..182d9aa3315 100644
--- a/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java
@@ -9818,6 +9818,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }
 
diff --git a/core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt b/core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt
index 6862ef8f30f..b45ad6a18b6 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt
@@ -71,7 +71,7 @@ interface ClassicTypeSystemContext : TypeSystemInferenceExtensionContext, TypeSy
 
     override fun SimpleTypeMarker.isStubType(): Boolean {
         require(this is SimpleType, this::errorMessage)
-        return this is StubType
+        return this is AbstractStubType
     }
 
     override fun CapturedTypeMarker.lowerType(): KotlinTypeMarker? {
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
index e07ea919ad8..a7858b36131 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java
@@ -8383,6 +8383,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }
 
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
index 6916004b760..55dc09c4d75 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java
@@ -8383,6 +8383,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }
 
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
index 129610bc9f8..9f5135cec9d 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
@@ -8383,6 +8383,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             public void testPropertyMetadata() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/propertyMetadata.kt");
             }
+
+            @TestMetadata("provideDelegateByExtensionFunction.kt")
+            public void testProvideDelegateByExtensionFunction() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/provideDelegate/provideDelegateByExtensionFunction.kt");
+            }
         }
     }