diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
index c2ef82a7066..1cdfbf871b0 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt
@@ -64,6 +64,8 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
             FirOpenMemberChecker,
             FirClassVarianceChecker,
             FirSealedSupertypeChecker,
+            FirMemberFunctionsChecker,
+            FirMemberPropertiesChecker,
         )
 
     override val regularClassCheckers: Set<FirRegularClassChecker>
@@ -83,8 +85,6 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
             FirPrimaryConstructorSuperTypeChecker,
             FirTypeParametersInObjectChecker,
             FirFunInterfaceDeclarationChecker,
-            FirMemberFunctionsChecker,
-            FirMemberPropertiesChecker,
             FirNestedClassChecker,
             FirInlineClassDeclarationChecker,
         )
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirDeclarationCheckerUtils.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirDeclarationCheckerUtils.kt
index d5ef28147c3..bdfac883321 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirDeclarationCheckerUtils.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirDeclarationCheckerUtils.kt
@@ -25,26 +25,26 @@ import org.jetbrains.kotlin.fir.symbols.impl.ConeClassLookupTagWithFixedSymbol
 import org.jetbrains.kotlin.fir.types.FirImplicitTypeRef
 import org.jetbrains.kotlin.lexer.KtTokens
 
-internal fun isInsideExpectClass(containingClass: FirRegularClass, context: CheckerContext): Boolean {
-    return isInsideSpecificClass(containingClass, context) { klass -> klass.isExpect }
+internal fun isInsideExpectClass(containingClass: FirClass, context: CheckerContext): Boolean {
+    return isInsideSpecificClass(containingClass, context) { klass -> klass is FirRegularClass && klass.isExpect }
 }
 
-internal fun isInsideExternalClass(containingClass: FirRegularClass, context: CheckerContext): Boolean {
-    return isInsideSpecificClass(containingClass, context) { klass -> klass.isExternal }
+internal fun isInsideExternalClass(containingClass: FirClass, context: CheckerContext): Boolean {
+    return isInsideSpecificClass(containingClass, context) { klass -> klass is FirRegularClass && klass.isExternal }
 }
 
 // Note that the class that contains the currently visiting declaration will *not* be in the context's containing declarations *yet*.
 private inline fun isInsideSpecificClass(
-    containingClass: FirRegularClass,
+    containingClass: FirClass,
     context: CheckerContext,
-    predicate: (FirRegularClass) -> Boolean
+    predicate: (FirClass) -> Boolean
 ): Boolean {
     return predicate.invoke(containingClass) ||
             context.containingDeclarations.asReversed().any { it is FirRegularClass && predicate.invoke(it) }
 }
 
 internal fun FirMemberDeclaration.isEffectivelyExpect(
-    containingClass: FirRegularClass?,
+    containingClass: FirClass?,
     context: CheckerContext,
 ): Boolean {
     if (this.isExpect) return true
@@ -53,7 +53,7 @@ internal fun FirMemberDeclaration.isEffectivelyExpect(
 }
 
 internal fun FirMemberDeclaration.isEffectivelyExternal(
-    containingClass: FirRegularClass?,
+    containingClass: FirClass?,
     context: CheckerContext,
 ): Boolean {
     if (this.isExternal) return true
@@ -93,7 +93,7 @@ internal fun checkExpectDeclarationVisibilityAndBody(
 
 // Matched FE 1.0's [DeclarationsChecker#checkPropertyInitializer].
 internal fun checkPropertyInitializer(
-    containingClass: FirRegularClass?,
+    containingClass: FirClass?,
     property: FirProperty,
     modifierList: FirModifierList?,
     isInitialized: Boolean,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionsChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionsChecker.kt
index a671e8ed350..4f586cb00ed 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionsChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberFunctionsChecker.kt
@@ -18,8 +18,8 @@ import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.lexer.KtTokens
 
 // See old FE's [DeclarationsChecker]
-object FirMemberFunctionsChecker : FirRegularClassChecker() {
-    override fun check(declaration: FirRegularClass, context: CheckerContext, reporter: DiagnosticReporter) {
+object FirMemberFunctionsChecker : FirClassChecker() {
+    override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
         for (member in declaration.declarations) {
             if (member is FirSimpleFunction) {
                 checkFunction(declaration, member, context, reporter)
@@ -28,7 +28,7 @@ object FirMemberFunctionsChecker : FirRegularClassChecker() {
     }
 
     private fun checkFunction(
-        containingDeclaration: FirRegularClass,
+        containingDeclaration: FirClass,
         function: FirSimpleFunction,
         context: CheckerContext,
         reporter: DiagnosticReporter
@@ -41,7 +41,7 @@ object FirMemberFunctionsChecker : FirRegularClassChecker() {
         val hasAbstractModifier = KtTokens.ABSTRACT_KEYWORD in modifierList
         val isAbstract = function.isAbstract || hasAbstractModifier
         if (isAbstract) {
-            if (!containingDeclaration.canHaveAbstractDeclaration) {
+            if (containingDeclaration is FirRegularClass && !containingDeclaration.canHaveAbstractDeclaration) {
                 reporter.reportOn(
                     source,
                     FirErrors.ABSTRACT_FUNCTION_IN_NON_ABSTRACT_CLASS,
diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberPropertiesChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberPropertiesChecker.kt
index 251c2511bbc..65b72ffa9f8 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberPropertiesChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirMemberPropertiesChecker.kt
@@ -30,8 +30,8 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
 import org.jetbrains.kotlin.lexer.KtTokens
 
 // See old FE's [DeclarationsChecker]
-object FirMemberPropertiesChecker : FirRegularClassChecker() {
-    override fun check(declaration: FirRegularClass, context: CheckerContext, reporter: DiagnosticReporter) {
+object FirMemberPropertiesChecker : FirClassChecker() {
+    override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
         val memberPropertySymbols = declaration.declarations.filterIsInstance<FirProperty>().map { it.symbol }.toSet()
         val initializedInConstructor =
             mutableMapOf<FirPropertySymbol, EventOccurrencesRange>().withDefault { EventOccurrencesRange.ZERO }
@@ -59,7 +59,7 @@ object FirMemberPropertiesChecker : FirRegularClassChecker() {
     }
 
     private fun collectPropertyInitialization(
-        klass: FirRegularClass,
+        klass: FirClass,
         memberPropertySymbols: Set<FirPropertySymbol>,
         initializedInConstructor: MutableMap<FirPropertySymbol, EventOccurrencesRange>,
         initializedInInitOrOtherProperty: MutableMap<FirPropertySymbol, EventOccurrencesRange>
@@ -144,7 +144,7 @@ object FirMemberPropertiesChecker : FirRegularClassChecker() {
     }
 
     private fun checkProperty(
-        containingDeclaration: FirRegularClass,
+        containingDeclaration: FirClass,
         property: FirProperty,
         isInitialized: Boolean,
         context: CheckerContext,
@@ -182,7 +182,7 @@ object FirMemberPropertiesChecker : FirRegularClassChecker() {
             }
 
             if (isAbstract) {
-                if (!containingDeclaration.canHaveAbstractDeclaration) {
+                if (containingDeclaration is FirRegularClass && !containingDeclaration.canHaveAbstractDeclaration) {
                     property.source?.let {
                         reporter.reportOn(
                             it,
@@ -216,7 +216,12 @@ object FirMemberPropertiesChecker : FirRegularClassChecker() {
         }
     }
 
-    private fun FirRegularClass.collectDeadEndDeclarations(): Set<FirElement> {
+    private fun FirClass.collectDeadEndDeclarations(): Set<FirElement> {
+        val controlFlowGraphReference = when (this) {
+            is FirAnonymousObject -> this.controlFlowGraphReference
+            is FirRegularClass -> this.controlFlowGraphReference
+            else -> null
+        }
         val cfg = controlFlowGraphReference?.controlFlowGraph ?: return emptySet()
         return cfg.exitNode.incomingEdges.keys
             .map { it.fir }
diff --git a/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt b/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt
index c1bae7ff55e..8c6aba4782d 100644
--- a/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt
+++ b/compiler/testData/diagnostics/tests/controlFlowAnalysis/UninitializedOrReassignedVariables.fir.kt
@@ -264,7 +264,7 @@ class ClassObject() {
 fun foo() {
     val a = object {
         val x : Int
-        val y : Int
+        <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>val y : Int<!>
         val z : Int
         init {
             x = 1
@@ -282,7 +282,7 @@ class TestObjectExpression() {
     fun foo() {
         val a = object {
             val x : Int
-            val y : Int
+            <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>val y : Int<!>
             init {
                 if (true)
                     x = 12