diff --git a/compiler/cli/cli-common/resources/META-INF/extensions/compiler.xml b/compiler/cli/cli-common/resources/META-INF/extensions/compiler.xml
index 5f59ff5b434..3f0f1f336e0 100644
--- a/compiler/cli/cli-common/resources/META-INF/extensions/compiler.xml
+++ b/compiler/cli/cli-common/resources/META-INF/extensions/compiler.xml
@@ -66,8 +66,8 @@
         <extensionPoint qualifiedName="org.jetbrains.kotlin.renameHandler"
                         interface="com.intellij.refactoring.rename.RenameHandler"
                         dynamic="true"/>
-        <extensionPoint qualifiedName="org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar"
-                        interface="org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar"/>
+        <extensionPoint qualifiedName="org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrarAdapter"
+                        interface="org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrarAdapter"/>
         <extensionPoint qualifiedName="org.jetbrains.kotlin.DescriptorSerializerPlugin"
                         interface="org.jetbrains.kotlin.serialization.DescriptorSerializerPlugin"/>
         <extensionPoint qualifiedName="org.jetbrains.kotlin.defaultErrorMessages"
diff --git a/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt b/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt
index 27e21563c5b..92877f1e09d 100644
--- a/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt
+++ b/compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt
@@ -82,7 +82,7 @@ import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.extensions.*
 import org.jetbrains.kotlin.extensions.internal.CandidateInterceptor
 import org.jetbrains.kotlin.extensions.internal.TypeResolutionInterceptor
-import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
+import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrarAdapter
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.js.translate.extensions.JsSyntheticTranslateExtension
 import org.jetbrains.kotlin.load.kotlin.KotlinBinaryClassCache
@@ -649,7 +649,7 @@ class KotlinCoreEnvironment private constructor(
             TypeResolutionInterceptor.registerExtensionPoint(project)
             CandidateInterceptor.registerExtensionPoint(project)
             DescriptorSerializerPlugin.registerExtensionPoint(project)
-            FirExtensionRegistrar.registerExtensionPoint(project)
+            FirExtensionRegistrarAdapter.registerExtensionPoint(project)
         }
 
         internal fun registerExtensionsFromPlugins(project: MockProject, configuration: CompilerConfiguration) {
diff --git a/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt b/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt
index 8f84b774d01..1337d122878 100644
--- a/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt
+++ b/compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt
@@ -5,17 +5,23 @@
 
 package org.jetbrains.kotlin.fir.extensions
 
-import org.jetbrains.kotlin.extensions.ProjectExtensionDescriptor
+import com.intellij.openapi.project.Project
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.SessionConfiguration
 import org.jetbrains.kotlin.fir.analysis.extensions.FirAdditionalCheckersExtension
 import kotlin.reflect.KClass
 
-abstract class FirExtensionRegistrar {
-    companion object : ProjectExtensionDescriptor<FirExtensionRegistrar>(
-        name = "org.jetbrains.kotlin.fir.extensions.firExtensionRegistrar",
-        extensionClass = FirExtensionRegistrar::class.java
-    ) {
+abstract class FirExtensionRegistrar : FirExtensionRegistrarAdapter() {
+    companion object {
+        fun getInstances(project: Project): List<FirExtensionRegistrar> {
+            @Suppress("UNCHECKED_CAST")
+            return FirExtensionRegistrarAdapter.getInstances(project) as List<FirExtensionRegistrar>
+        }
+
+        fun registerExtension(project: Project, extension: FirExtensionRegistrar) {
+            FirExtensionRegistrarAdapter.registerExtension(project, extension)
+        }
+
         internal val AVAILABLE_EXTENSIONS = listOf(
             FirStatusTransformerExtension::class,
             FirDeclarationGenerationExtension::class,
diff --git a/compiler/frontend.common/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrarAdapter.kt b/compiler/frontend.common/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrarAdapter.kt
new file mode 100644
index 00000000000..7c515ed5294
--- /dev/null
+++ b/compiler/frontend.common/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrarAdapter.kt
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2021 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.extensions
+
+import org.jetbrains.kotlin.extensions.ProjectExtensionDescriptor
+
+/*
+ * This is needed to prevent ClassNotFoundExceptions in IDE plugin built on FE 1.0
+ *
+ * Actual FirExtensionRegistrar uses some specific classes from FIR, so if we reference
+ *   it in KotlinCoreEnvironment (where all extension points are registered) then we
+ *   need to have all FIR compiler on classpath. And in IDE plugin we don't depend
+ *   on FIR to reduce plugin size.
+ */
+abstract class FirExtensionRegistrarAdapter {
+    companion object : ProjectExtensionDescriptor<FirExtensionRegistrarAdapter>(
+        name = "org.jetbrains.kotlin.fir.extensions.firExtensionRegistrar",
+        extensionClass = FirExtensionRegistrarAdapter::class.java
+    )
+}