diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt
index 438d5275fcd..e4a1ef90c36 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrDeclarationDeserializer.kt
@@ -286,7 +286,7 @@ class IrDeclarationDeserializer(
 
         // make sure this symbol is known to linker
         symbolDeserializer.referenceLocalIrSymbol(result.symbol, sig)
-        result.annotations += deserializeAnnotations(proto.base.annotationList)
+        result.annotations = deserializeAnnotations(proto.base.annotationList)
         result.parent = currentParent
         return result
     }
diff --git a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSymbolDeserializer.kt b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSymbolDeserializer.kt
index e28266aaead..2021d815eab 100644
--- a/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSymbolDeserializer.kt
+++ b/compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrSymbolDeserializer.kt
@@ -73,7 +73,7 @@ class IrSymbolDeserializer(
     }
 
     fun referenceLocalIrSymbol(symbol: IrSymbol, signature: IdSignature) {
-        deserializedSymbols.putIfAbsent(signature, symbol)
+        deserializedSymbols.put(signature, symbol)
     }
 
     fun referenceSimpleFunctionByLocalSignature(idSignature: IdSignature) : IrSimpleFunctionSymbol =