diff --git a/plugins/fir/fir-plugin-prototype/plugin-annotations/src/org/jetbrains/kotlin/fir/plugin/LibraryClassWithNestedClass.kt b/plugins/fir/fir-plugin-prototype/plugin-annotations/src/org/jetbrains/kotlin/fir/plugin/LibraryClassWithNestedClass.kt
new file mode 100644
index 00000000000..770926efc4d
--- /dev/null
+++ b/plugins/fir/fir-plugin-prototype/plugin-annotations/src/org/jetbrains/kotlin/fir/plugin/LibraryClassWithNestedClass.kt
@@ -0,0 +1,12 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.plugin
+
+abstract class LibraryClassWithNestedClass {
+    open class NestedClass {
+        fun foo() {}
+    }
+}
\ No newline at end of file
diff --git a/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/AllOpenSupertypeGenerator.kt b/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/AllOpenSupertypeGenerator.kt
new file mode 100644
index 00000000000..779cbfc17d1
--- /dev/null
+++ b/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/AllOpenSupertypeGenerator.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.plugin
+
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.declarations.FirClassLikeDeclaration
+import org.jetbrains.kotlin.fir.declarations.FirPluginKey
+import org.jetbrains.kotlin.fir.extensions.FirSupertypeGenerationExtension
+import org.jetbrains.kotlin.fir.extensions.predicate.DeclarationPredicate
+import org.jetbrains.kotlin.fir.extensions.predicate.has
+import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.FirTypeRef
+import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.constructClassLikeType
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+
+class AllOpenSupertypeGenerator(session: FirSession) : FirSupertypeGenerationExtension(session) {
+    companion object {
+        private val newSupertypeClassId = ClassId(FqName("org.jetbrains.kotlin.fir.plugin"), Name.identifier("LibraryClassWithNestedClass"))
+    }
+
+    override fun computeAdditionalSupertypes(
+        classLikeDeclaration: FirClassLikeDeclaration<*>,
+        resolvedSupertypes: List<FirTypeRef>
+    ): List<FirResolvedTypeRef> {
+        return listOf(
+            buildResolvedTypeRef {
+                type = newSupertypeClassId.constructClassLikeType(emptyArray(), isNullable = false)
+            }
+        )
+    }
+
+    override val key: FirPluginKey
+        get() = AllOpenPluginKey
+
+    override val predicate: DeclarationPredicate = has("C".fqn())
+}
\ No newline at end of file
diff --git a/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/FirAllOpenComponentRegistrar.kt b/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/FirAllOpenComponentRegistrar.kt
index 5c776f5affd..df552c39070 100644
--- a/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/FirAllOpenComponentRegistrar.kt
+++ b/plugins/fir/fir-plugin-prototype/src/org/jetbrains/kotlin/fir/plugin/FirAllOpenComponentRegistrar.kt
@@ -6,14 +6,14 @@
 package org.jetbrains.kotlin.fir.plugin
 
 import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-import org.jetbrains.kotlin.fir.plugin.generators.AllOpenMemberGenerator
-import org.jetbrains.kotlin.fir.plugin.generators.AllOpenNestedClassGenerator
-import org.jetbrains.kotlin.fir.plugin.generators.AllOpenRecursiveNestedClassGenerator
-import org.jetbrains.kotlin.fir.plugin.generators.AllOpenTopLevelDeclarationsGenerator
+import org.jetbrains.kotlin.fir.plugin.generators.*
 
 class FirAllOpenComponentRegistrar : FirExtensionRegistrar() {
     override fun ExtensionRegistrarContext.configurePlugin() {
         +::AllOpenStatusTransformer
+        +::AllOpenSupertypeGenerator
+
+        // Declaration generators
         +::AllOpenMemberGenerator
         +::AllOpenNestedClassGenerator
         +::AllOpenAdditionalCheckers
diff --git a/plugins/fir/fir-plugin-prototype/testData/supertypes/simple.kt b/plugins/fir/fir-plugin-prototype/testData/supertypes/simple.kt
new file mode 100644
index 00000000000..ecc4a2e34a5
--- /dev/null
+++ b/plugins/fir/fir-plugin-prototype/testData/supertypes/simple.kt
@@ -0,0 +1,10 @@
+import org.jetbrains.kotlin.fir.plugin.C
+
+@C
+class A {
+    class MyNested : NestedClass()
+
+    fun test() {
+        MyNested().foo()
+    }
+}
\ No newline at end of file
diff --git a/plugins/fir/fir-plugin-prototype/testData/supertypes/simple.txt b/plugins/fir/fir-plugin-prototype/testData/supertypes/simple.txt
new file mode 100644
index 00000000000..abcd7654284
--- /dev/null
+++ b/plugins/fir/fir-plugin-prototype/testData/supertypes/simple.txt
@@ -0,0 +1,18 @@
+FILE: simple.kt
+    @R|org/jetbrains/kotlin/fir/plugin/C|() public final class A : R|kotlin/Any| {
+        public constructor(): R|A| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final class MyNested : R|org/jetbrains/kotlin/fir/plugin/LibraryClassWithNestedClass.NestedClass| {
+            public constructor(): R|A.MyNested| {
+                super<R|ERROR CLASS: Symbol not found, for `NestedClass`|>()
+            }
+
+        }
+
+        public final fun test(): R|kotlin/Unit| {
+            R|/A.MyNested.MyNested|().R|org/jetbrains/kotlin/fir/plugin/LibraryClassWithNestedClass.NestedClass.foo|()
+        }
+
+    }
diff --git a/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/FirAllOpenDiagnosticTestGenerated.java b/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/FirAllOpenDiagnosticTestGenerated.java
index e2852caa92f..bbcc55dbc00 100644
--- a/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/FirAllOpenDiagnosticTestGenerated.java
+++ b/plugins/fir/fir-plugin-prototype/tests/org/jetbrains/kotlin/fir/plugin/FirAllOpenDiagnosticTestGenerated.java
@@ -101,4 +101,22 @@ public class FirAllOpenDiagnosticTestGenerated extends AbstractFirAllOpenDiagnos
             runTest("plugins/fir/fir-plugin-prototype/testData/status/simpleAnnotation.kt");
         }
     }
+
+    @TestMetadata("plugins/fir/fir-plugin-prototype/testData/supertypes")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Supertypes extends AbstractFirAllOpenDiagnosticTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInSupertypes() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("plugins/fir/fir-plugin-prototype/testData/supertypes"), Pattern.compile("^(.+)\\.kt$"), null, true);
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("plugins/fir/fir-plugin-prototype/testData/supertypes/simple.kt");
+        }
+    }
 }