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 3a5ce956106..7c4a9b4d6ee 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
@@ -10,7 +10,10 @@ import org.jetbrains.kotlin.ir.builders.createTmpVariable
 import org.jetbrains.kotlin.ir.builders.irGet
 import org.jetbrains.kotlin.ir.declarations.IrClass
 import org.jetbrains.kotlin.ir.declarations.IrVariable
-import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.IrConst
+import org.jetbrains.kotlin.ir.expressions.IrConstKind
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.IrGetValue
 import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.types.IrType
@@ -19,6 +22,7 @@ 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.isTrivial
+import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.util.OperatorNameConventions
 
@@ -105,7 +109,8 @@ internal fun IrExpression.castIfNecessary(targetClass: IrClass) =
         this
     } else {
         val numberCastFunctionName = Name.identifier("to${targetClass.name.asString()}")
-        val castFun = type.getClass()!!.functions.single {
+        val classifier = type.getClass() ?: error("Has to be a class ${type.render()}")
+        val castFun = classifier.functions.single {
             it.name == numberCastFunctionName &&
                     it.dispatchReceiverParameter != null && it.extensionReceiverParameter == null && it.valueParameters.isEmpty()
         }