diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt
index 46645dc42dc..6ebdb686399 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/IrUtils.kt
@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.descriptors.*
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrDelegatingConstructorCallImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrErrorExpressionImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrGetValueImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrInstanceInitializerCallImpl
 import org.jetbrains.kotlin.ir.overrides.FakeOverrideBuilderStrategy
@@ -694,4 +695,10 @@ fun IrExpression?.isPure(
     }
 
     return false
-}
\ No newline at end of file
+}
+
+fun IrExpression.isTrivial() =
+    this is IrConst<*> ||
+            this is IrGetValue ||
+            this is IrGetObjectValue ||
+            this is IrErrorExpressionImpl
\ No newline at end of file
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt
index 8f48c790cc4..0bf77f8637d 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/IfNullExpressionsFusionLowering.kt
@@ -7,6 +7,8 @@ package org.jetbrains.kotlin.backend.common.lower
 
 import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import org.jetbrains.kotlin.backend.common.FileLoweringPass
+import org.jetbrains.kotlin.backend.common.ir.isTrivial
+import org.jetbrains.kotlin.backend.common.lower.loops.canHaveSideEffects
 import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
 import org.jetbrains.kotlin.ir.builders.createTmpVariable
 import org.jetbrains.kotlin.ir.builders.irBlock
@@ -14,11 +16,13 @@ import org.jetbrains.kotlin.ir.builders.irGet
 import org.jetbrains.kotlin.ir.builders.irIfNull
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrErrorExpressionImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrTypeOperatorCallImpl
 import org.jetbrains.kotlin.ir.symbols.IrVariableSymbol
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.isNullable
 import org.jetbrains.kotlin.ir.util.fileOrNull
+import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 
@@ -189,11 +193,13 @@ class IfNullExpressionsFusionLowering(val context: CommonBackendContext) : FileL
             null
     }
 
-    private fun IrExpression.isTrivial() =
-        this is IrExpressionWithCopy
-
     private fun IrExpression.copyIfTrivial() =
-        if (this is IrExpressionWithCopy) copy() else this
+        if (isTrivial()) {
+            require(this is IrExpressionWithCopy) {
+                "Not a copyable expression: ${render()}"
+            }
+            copy()
+        } else this
 
     private fun IrExpression.remap(from: IrVariable, to: Lazy<IrVariable>): IrExpression =
         copyIfTrivial().transform(object : AbstractVariableRemapper() {
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/Utils.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/Utils.kt
index 83f38b6f83e..97a4cef914e 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/Utils.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/Utils.kt
@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.backend.common.lower.loops
 
+import org.jetbrains.kotlin.backend.common.ir.isTrivial
 import org.jetbrains.kotlin.backend.common.lower.DeclarationIrBuilder
 import org.jetbrains.kotlin.ir.builders.createTmpVariable
 import org.jetbrains.kotlin.ir.builders.irGet
@@ -13,11 +14,13 @@ import org.jetbrains.kotlin.ir.declarations.IrVariable
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrErrorExpressionImpl
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.getClass
 import org.jetbrains.kotlin.ir.types.isNothing
 import org.jetbrains.kotlin.ir.util.defaultType
 import org.jetbrains.kotlin.ir.util.functions
+import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.util.OperatorNameConventions
 
@@ -70,7 +73,7 @@ internal fun IrExpression.decrement(): IrExpression {
 }
 
 internal val IrExpression.canHaveSideEffects: Boolean
-    get() = this !is IrExpressionWithCopy
+    get() = !isTrivial()
 
 private fun Any?.toLong(): Long? =
     when (this) {
@@ -95,9 +98,12 @@ internal fun DeclarationIrBuilder.createTemporaryVariableIfNecessary(
     expression: IrExpression, nameHint: String? = null,
     irType: IrType? = null, isMutable: Boolean = false
 ): Pair<IrVariable?, IrExpressionWithCopy> =
-    if (expression !is IrExpressionWithCopy) {
+    if (expression.canHaveSideEffects) {
         scope.createTmpVariable(expression, nameHint = nameHint, irType = irType, isMutable = isMutable).let { Pair(it, irGet(it)) }
     } else {
+        require(expression is IrExpressionWithCopy) {
+            "Not a copyable expression: ${expression.render()}"
+        }
         Pair(null, expression)
     }