diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/Utils.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/Utils.kt
index 64cb1333ecc..6bf40f6c321 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/Utils.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/Utils.kt
@@ -15,29 +15,12 @@ import org.jetbrains.kotlin.fir.declarations.impl.FirModifiableClass
 import org.jetbrains.kotlin.fir.declarations.modality
 import org.jetbrains.kotlin.fir.expressions.FirBlock
 import org.jetbrains.kotlin.fir.expressions.FirExpression
-import org.jetbrains.kotlin.fir.expressions.FirExpressionWithSmartcast
-import org.jetbrains.kotlin.fir.expressions.FirWhenSubjectExpression
 
 fun ModuleInfo.dependenciesWithoutSelf(): Sequence<ModuleInfo> = dependencies().asSequence().filter { it != this }
 
 // TODO: rewrite
 fun FirBlock.returnExpressions(): List<FirExpression> = listOfNotNull(statements.lastOrNull() as? FirExpression)
 
-fun FirElement.unwrapWhenSubjectExpression(): FirElement = if (this is FirWhenSubjectExpression) {
-    val whenExpression = whenSubject.whenExpression
-    whenExpression.subjectVariable
-        ?: whenExpression.subject
-        ?: throw IllegalStateException("Subject or subject variable must be not null")
-} else {
-    this
-}
-
-tailrec fun FirElement.unwrapSmartcast(): FirElement = if (this is FirExpressionWithSmartcast) {
-    originalExpression.unwrapSmartcast()
-} else {
-    this
-}
-
 private val PUBLIC_METHOD_NAMES_IN_OBJECT = setOf("equals", "hashCode", "getClass", "wait", "notify", "notifyAll", "toString")
 
 fun FirModifiableClass<FirRegularClass>.calculateSAM() {