diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt
index 809800cec15..3c2ddb42e66 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocReference.kt
@@ -46,9 +46,9 @@ class KDocReference(element: KDocName): KtMultiReference<KDocName>(element) {
 
     override fun resolve(): PsiElement? = multiResolve(false).firstOrNull()?.element
 
-    override fun handleElementRename(newElementName: String?): PsiElement? {
+    override fun handleElementRename(newElementName: String): PsiElement? {
         val textRange = element.getNameTextRange()
-        val newText = textRange.replace(element.text, newElementName!!)
+        val newText = textRange.replace(element.text, newElementName)
         val newLink = KDocElementFactory(element.project).createNameFromText(newText)
         return element.replace(newLink)
     }
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtArrayAccessReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtArrayAccessReference.kt
index cfa58011013..86b7bae9557 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtArrayAccessReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtArrayAccessReference.kt
@@ -54,7 +54,7 @@ class KtArrayAccessReference(
 
     override fun canRename() = true
 
-    override fun handleElementRename(newElementName: String?): PsiElement? {
+    override fun handleElementRename(newElementName: String): PsiElement? {
         val arrayAccessExpression = expression
         if (OperatorNameConventions.INVOKE.asString() == newElementName) {
             val replacement = KtPsiFactory(arrayAccessExpression.project).buildExpression {
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtDestructuringDeclarationReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtDestructuringDeclarationReference.kt
index 88d6cb2a158..52a60fc3bf4 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtDestructuringDeclarationReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtDestructuringDeclarationReference.kt
@@ -39,7 +39,7 @@ class KtDestructuringDeclarationReference(element: KtDestructuringDeclarationEnt
         return resolveToDescriptors(bindingContext).all { it is CallableMemberDescriptor && it.kind == CallableMemberDescriptor.Kind.SYNTHESIZED}
     }
 
-    override fun handleElementRename(newElementName: String?): PsiElement? {
+    override fun handleElementRename(newElementName: String): PsiElement? {
         if (canRename()) return expression
         throw IncorrectOperationException()
     }
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtInvokeFunctionReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtInvokeFunctionReference.kt
index eff19bed6c9..3763d61b973 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtInvokeFunctionReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtInvokeFunctionReference.kt
@@ -94,7 +94,7 @@ class KtInvokeFunctionReference(expression: KtCallExpression) : KtSimpleReferenc
 
     override fun canRename(): Boolean = true
 
-    override fun handleElementRename(newElementName: String?): PsiElement? {
+    override fun handleElementRename(newElementName: String): PsiElement? {
         val callExpression = expression
         val fullCallExpression = callExpression.getQualifiedExpressionForSelectorOrThis()
         if (newElementName == OperatorNameConventions.GET.asString() && callExpression.typeArguments.isEmpty()) {
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtReference.kt
index 38f31402254..5ae9f034732 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtReference.kt
@@ -56,7 +56,7 @@ abstract class AbstractKtReference<T : KtElement>(element: T) : PsiPolyVariantRe
     override fun getCanonicalText(): String = "<TBD>"
 
     open fun canRename(): Boolean = false
-    override fun handleElementRename(newElementName: String?): PsiElement? = throw IncorrectOperationException()
+    override fun handleElementRename(newElementName: String): PsiElement? = throw IncorrectOperationException()
 
     override fun bindToElement(element: PsiElement): PsiElement = throw IncorrectOperationException()
 
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtSimpleNameReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtSimpleNameReference.kt
index 0980d267dbe..fd7d61cc34e 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtSimpleNameReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/KtSimpleNameReference.kt
@@ -100,9 +100,8 @@ class KtSimpleNameReference(expression: KtSimpleNameExpression) : KtSimpleRefere
         return true
     }
 
-    override fun handleElementRename(newElementName: String?): PsiElement {
+    override fun handleElementRename(newElementName: String): PsiElement {
         if (!canRename()) throw IncorrectOperationException()
-        if (newElementName == null) return expression
 
         if (newElementName.unquote() == "") {
             val qualifiedElement = expression.getQualifiedElement()
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/SyntheticPropertyAccessorReference.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/SyntheticPropertyAccessorReference.kt
index 66cf1adb200..97e7b304e96 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/SyntheticPropertyAccessorReference.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/SyntheticPropertyAccessorReference.kt
@@ -105,8 +105,8 @@ sealed class SyntheticPropertyAccessorReference(expression: KtNameReferenceExpre
         }
     }
 
-    override fun handleElementRename(newElementName: String?): PsiElement? {
-        if (!Name.isValidIdentifier(newElementName!!)) return expression
+    override fun handleElementRename(newElementName: String): PsiElement? {
+        if (!Name.isValidIdentifier(newElementName)) return expression
 
         val newNameAsName = Name.identifier(newElementName)
         val newName = if (getter) {