diff --git a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt
index ee8dfb4f50f..53f8a2697b1 100644
--- a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt
+++ b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/lazy/Fir2IrLazyClass.kt
@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.ir.declarations.lazy.IrMaybeDeserializedClass
 import org.jetbrains.kotlin.ir.declarations.lazy.lazyVar
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.impl.IrSimpleTypeImpl
@@ -154,6 +155,7 @@ class Fir2IrLazyClass(
             .also(converter::bindFakeOverridesOrPostpone)
     }
 
+    @IrSymbolInternals
     override val declarations: MutableList<IrDeclaration> by lazyVar(lock) {
         val result = mutableListOf<IrDeclaration>()
         // NB: it's necessary to take all callables from scope,
diff --git a/compiler/ir/ir.tree/gen/org/jetbrains/kotlin/ir/declarations/IrDeclarationContainer.kt b/compiler/ir/ir.tree/gen/org/jetbrains/kotlin/ir/declarations/IrDeclarationContainer.kt
index acc533b3b44..4af7d164be1 100644
--- a/compiler/ir/ir.tree/gen/org/jetbrains/kotlin/ir/declarations/IrDeclarationContainer.kt
+++ b/compiler/ir/ir.tree/gen/org/jetbrains/kotlin/ir/declarations/IrDeclarationContainer.kt
@@ -8,6 +8,7 @@
 
 package org.jetbrains.kotlin.ir.declarations
 
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 
 /**
  * A non-leaf IR tree element.
@@ -15,5 +16,12 @@ package org.jetbrains.kotlin.ir.declarations
  * Generated from: [org.jetbrains.kotlin.ir.generator.IrTree.declarationContainer]
  */
 interface IrDeclarationContainer : IrDeclarationParent {
+    /**
+     * Accessing list of declaration may trigger lazy declaration list computation for lazy class,
+     *   which requires computation of fake-overrides for this class. So it's unsafe to access it
+     *   before IR for all sources is built (because fake-overrides of lazy classes may depend on
+     *   declaration of source classes, e.g. for java source classes)
+     */
+    @IrSymbolInternals
     val declarations: MutableList<IrDeclaration>
 }
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
index d142e1b3cd7..4e68a138dfc 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrClassImpl.kt
@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.name.Name
@@ -47,6 +48,7 @@ open class IrClassImpl(
 
     override var thisReceiver: IrValueParameter? = null
 
+    @IrSymbolInternals
     override val declarations: MutableList<IrDeclaration> = ArrayList()
 
     override var typeParameters: List<IrTypeParameter> = emptyList()
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrExternalPackageFragmentImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrExternalPackageFragmentImpl.kt
index a41392766fc..57a906672ea 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrExternalPackageFragmentImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrExternalPackageFragmentImpl.kt
@@ -24,6 +24,7 @@ import org.jetbrains.kotlin.ir.UNDEFINED_OFFSET
 import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrExternalPackageFragment
 import org.jetbrains.kotlin.ir.symbols.IrExternalPackageFragmentSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.symbols.impl.IrExternalPackageFragmentSymbolImpl
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedContainerSource
@@ -51,6 +52,7 @@ class IrExternalPackageFragmentImpl(
     override val moduleDescriptor: ModuleDescriptor
         get() = packageFragmentDescriptor.containingDeclaration
 
+    @IrSymbolInternals
     override val declarations: MutableList<IrDeclaration> = ArrayList()
 
     @OptIn(ObsoleteDescriptorBasedAPI::class)
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt
index 93efec29c50..88aa5d8032d 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/impl/IrFileImpl.kt
@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
 import org.jetbrains.kotlin.ir.declarations.MetadataSource
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrFileSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.symbols.impl.IrFileSymbolImpl
 import org.jetbrains.kotlin.name.FqName
 
@@ -79,6 +80,7 @@ class IrFileImpl(
                 packageFragmentDescriptor.containingDeclaration
         }
 
+    @IrSymbolInternals
     override val declarations: MutableList<IrDeclaration> = ArrayList()
 
     override var annotations: List<IrConstructorCall> = emptyList()
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt
index 9f35d63930a..4bd2a83e64b 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/declarations/lazy/IrLazyClass.kt
@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.types.IrSimpleType
 import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.util.*
@@ -55,7 +56,7 @@ class IrLazyClass(
         }
     }
 
-
+    @IrSymbolInternals
     override val declarations: MutableList<IrDeclaration> by lazyVar(stubGenerator.lock) {
         ArrayList<IrDeclaration>().also {
             typeTranslator.buildWithScope(this) {
diff --git a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/impl/IrErrorClassImpl.kt b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/impl/IrErrorClassImpl.kt
index badc006c5dc..33942d717cc 100644
--- a/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/impl/IrErrorClassImpl.kt
+++ b/compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/types/impl/IrErrorClassImpl.kt
@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.impl.IrClassImpl
 import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
 import org.jetbrains.kotlin.ir.symbols.IrFileSymbol
+import org.jetbrains.kotlin.ir.symbols.IrSymbolInternals
 import org.jetbrains.kotlin.ir.symbols.impl.IrClassSymbolImpl
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
@@ -31,6 +32,8 @@ object IrErrorClassImpl : IrClassImpl(
             override var annotations: List<IrConstructorCall>
                 get() = shouldNotBeCalled()
                 set(_) {}
+
+            @IrSymbolInternals
             override val declarations: MutableList<IrDeclaration>
                 get() = shouldNotBeCalled()
             override val symbol: IrFileSymbol
diff --git a/compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt b/compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt
index f2b4fe5034b..1bd17e76fde 100644
--- a/compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt
+++ b/compiler/ir/ir.tree/tree-generator/src/org/jetbrains/kotlin/ir/generator/IrTree.kt
@@ -343,7 +343,17 @@ object IrTree : AbstractTreeBuilder() {
 
         parent(declarationParent)
 
-        +listField("declarations", declaration, mutability = List, isChild = true)
+        +listField("declarations", declaration, mutability = List, isChild = true) {
+            kDoc = """
+                 Accessing list of declaration may trigger lazy declaration list computation for lazy class,
+                   which requires computation of fake-overrides for this class. So it's unsafe to access it
+                   before IR for all sources is built (because fake-overrides of lazy classes may depend on
+                   declaration of source classes, e.g. for java source classes)
+            """.trimIndent()
+            generationCallback = {
+                addAnnotation(ClassName("org.jetbrains.kotlin.ir.symbols", "IrSymbolInternals"))
+            }
+        }
     }
     val typeParametersContainer: ElementConfig by element(Declaration) {
         ownsChildren = false