diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/NamingConventionInspections.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/NamingConventionInspections.kt
index 6b556f77e8f..88e423cdccd 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/NamingConventionInspections.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/NamingConventionInspections.kt
@@ -259,7 +259,7 @@ class NamingConventionOptionsPanel(owner: NamingConventionInspection) : JPanel()
             setOneLineMode(true)
         }
         regexField.document.addDocumentListener(object : DocumentAdapter() {
-            override fun documentChanged(e: DocumentEvent?) {
+            override fun documentChanged(e: DocumentEvent) {
                 owner.namePattern = regexField.text
             }
         })
diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/PlatformExtensionReceiverOfInlineInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/PlatformExtensionReceiverOfInlineInspection.kt
index 362d65ab279..2cacccab752 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/PlatformExtensionReceiverOfInlineInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/PlatformExtensionReceiverOfInlineInspection.kt
@@ -82,7 +82,7 @@ class PlatformExtensionReceiverOfInlineInspection : AbstractKotlinInspection() {
                 setOneLineMode(true)
             }
             regexField.document.addDocumentListener(object : DocumentListener {
-                override fun documentChanged(e: DocumentEvent?) {
+                override fun documentChanged(e: DocumentEvent) {
                     owner.namePattern = regexField.text
                 }
             })
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/ui/KotlinChangeSignatureDialog.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/ui/KotlinChangeSignatureDialog.kt
index 59d618977a3..b14df1925f0 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/ui/KotlinChangeSignatureDialog.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/ui/KotlinChangeSignatureDialog.kt
@@ -227,7 +227,7 @@ class KotlinChangeSignatureDialog(
                     if (editor != null) {
                         editor.addDocumentListener(
                                 object : DocumentAdapter() {
-                                    override fun documentChanged(e: DocumentEvent?) {
+                                    override fun documentChanged(e: DocumentEvent) {
                                         fireDocumentChanged(e, columnFinal)
                                     }
                                 }