diff --git a/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt b/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt
index 228bda7236f..8867c2d1288 100644
--- a/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt
+++ b/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt
@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.ir.expressions.impl
 
-import org.jetbrains.kotlin.ir.IrElementBase
 import org.jetbrains.kotlin.ir.IrStatement
 import org.jetbrains.kotlin.ir.declarations.IrFactory
 import org.jetbrains.kotlin.ir.declarations.impl.IrFactoryImpl
@@ -25,7 +24,7 @@ import org.jetbrains.kotlin.ir.expressions.IrBlockBody
 class IrBlockBodyImpl(
     override val startOffset: Int,
     override val endOffset: Int
-) : IrElementBase(), IrBlockBody {
+) : IrBlockBody() {
     constructor(startOffset: Int, endOffset: Int, statements: List<IrStatement>) : this(startOffset, endOffset) {
         this.statements.addAll(statements)
     }
diff --git a/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt b/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt
index bcb52427eca..328778c6b20 100644
--- a/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt
+++ b/compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt
@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.ir.expressions.impl
 
-import org.jetbrains.kotlin.ir.IrElementBase
 import org.jetbrains.kotlin.ir.declarations.IrFactory
 import org.jetbrains.kotlin.ir.declarations.impl.IrFactoryImpl
 import org.jetbrains.kotlin.ir.expressions.IrExpression
@@ -26,7 +25,7 @@ class IrExpressionBodyImpl(
     override val startOffset: Int,
     override val endOffset: Int,
     initializer: (IrExpressionBody.() -> Unit)? = null
-) : IrElementBase(), IrExpressionBody {
+) : IrExpressionBody() {
     init {
         initializer?.invoke(this)
     }
diff --git a/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrBlockBody.kt b/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrBlockBody.kt
index 9454b54f1ce..cf82524f88e 100644
--- a/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrBlockBody.kt
+++ b/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrBlockBody.kt
@@ -29,10 +29,7 @@ internal class PersistentIrBlockBody(
     override val startOffset: Int,
     override val endOffset: Int,
     override var initializer: (PersistentIrBlockBody.() -> Unit)? = null
-) :
-    PersistentIrBodyBase<PersistentIrBlockBody>,
-    IrBlockBody {
-
+) : IrBlockBody(), PersistentIrBodyBase<PersistentIrBlockBody> {
     override var lastModified: Int = stageController.currentStage
     override var loweredUpTo: Int = stageController.currentStage
     override var values: Array<Carrier>? = null
diff --git a/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrExpressionBody.kt b/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrExpressionBody.kt
index 7187531278e..9bb3540d55a 100644
--- a/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrExpressionBody.kt
+++ b/compiler/ir/ir.tree.persistent/src/org/jetbrains/kotlin/ir/expressions/persistent/PersistentIrExpressionBody.kt
@@ -30,10 +30,7 @@ internal class PersistentIrExpressionBody private constructor(
     override val endOffset: Int,
     private var expressionField: IrExpression? = null,
     override var initializer: (PersistentIrExpressionBody.() -> Unit)? = null
-) :
-    PersistentIrBodyBase<PersistentIrExpressionBody>,
-    IrExpressionBody {
-
+) : IrExpressionBody(), PersistentIrBodyBase<PersistentIrExpressionBody> {
     override var lastModified: Int = stageController.currentStage
     override var loweredUpTo: Int = stageController.currentStage
     override var values: Array<Carrier>? = null
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrBody.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrBody.kt
index 73a25f6a9b5..551b58773cd 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrBody.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/IrBody.kt
@@ -16,20 +16,20 @@
 
 package org.jetbrains.kotlin.ir.expressions
 
-import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.IrElementBase
 import org.jetbrains.kotlin.ir.declarations.IrFactory
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 
-interface IrBody : IrElement {
+abstract class IrBody : IrElementBase() {
     override fun <D> transform(transformer: IrElementTransformer<D>, data: D): IrBody =
         accept(transformer, data) as IrBody
 }
 
-interface IrExpressionBody : IrBody {
-    val factory: IrFactory
+abstract class IrExpressionBody : IrBody() {
+    abstract val factory: IrFactory
 
-    var expression: IrExpression
+    abstract var expression: IrExpression
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =
         visitor.visitExpressionBody(this, data)
@@ -46,8 +46,8 @@ interface IrExpressionBody : IrBody {
     }
 }
 
-interface IrBlockBody : IrBody, IrStatementContainer {
-    val factory: IrFactory
+abstract class IrBlockBody : IrBody(), IrStatementContainer {
+    abstract val factory: IrFactory
 
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R =
         visitor.visitBlockBody(this, data)
@@ -63,8 +63,8 @@ interface IrBlockBody : IrBody, IrStatementContainer {
     }
 }
 
-interface IrSyntheticBody : IrBody {
-    val kind: IrSyntheticBodyKind
+abstract class IrSyntheticBody : IrBody() {
+    abstract val kind: IrSyntheticBodyKind
 }
 
 enum class IrSyntheticBodyKind {
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSyntheticBodyImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSyntheticBodyImpl.kt
index 3e252bf5bb6..6104ce64b3d 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSyntheticBodyImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/expressions/impl/IrSyntheticBodyImpl.kt
@@ -16,7 +16,6 @@
 
 package org.jetbrains.kotlin.ir.expressions.impl
 
-import org.jetbrains.kotlin.ir.IrElementBase
 import org.jetbrains.kotlin.ir.expressions.IrSyntheticBody
 import org.jetbrains.kotlin.ir.expressions.IrSyntheticBodyKind
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformer
@@ -26,7 +25,7 @@ class IrSyntheticBodyImpl(
     override val startOffset: Int,
     override val endOffset: Int,
     override val kind: IrSyntheticBodyKind
-) : IrElementBase(), IrSyntheticBody {
+) : IrSyntheticBody() {
     override fun <R, D> accept(visitor: IrElementVisitor<R, D>, data: D): R {
         return visitor.visitSyntheticBody(this, data)
     }