diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/FirBuildersUtils.kt b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/FirBuildersUtils.kt
index cd794d993c4..3a9830415e3 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/FirBuildersUtils.kt
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/FirBuildersUtils.kt
@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
 import org.jetbrains.kotlin.fir.types.constructClassLikeType
+import org.jetbrains.kotlin.fir.types.toFirResolvedTypeRef
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.types.Variance
 import org.jetbrains.kotlinx.serialization.compiler.resolve.SerialEntityNames
@@ -38,7 +39,9 @@ fun FirDeclarationGenerationExtension.buildPrimaryConstructor(owner: FirClassSym
     return buildPrimaryConstructor {
         moduleData = session.moduleData
         origin = key.origin
-        returnTypeRef = owner.defaultType().newRef()
+        returnTypeRef = run {
+            owner.defaultType().toFirResolvedTypeRef()
+        }
         this.status = status
         symbol = FirConstructorSymbol(classId)
         if (isInner && classId.isNestedClass) {
@@ -52,10 +55,6 @@ fun FirDeclarationGenerationExtension.buildPrimaryConstructor(owner: FirClassSym
     }
 }
 
-fun ConeKotlinType.newRef(): FirResolvedTypeRef = buildResolvedTypeRef {
-    type = this@newRef
-}
-
 fun newSimpleTypeParameter(firSession: FirSession, containingDeclarationSymbol: FirBasedSymbol<*>, name: Name) = buildTypeParameter {
     moduleData = firSession.moduleData
     origin = SerializationPluginKey.origin
diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/SerializationFirResolveExtension.kt b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/SerializationFirResolveExtension.kt
index 81868dd62c5..c1e346fe51d 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/SerializationFirResolveExtension.kt
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/src/org/jetbrains/kotlinx/serialization/compiler/fir/SerializationFirResolveExtension.kt
@@ -30,11 +30,8 @@ import org.jetbrains.kotlin.fir.scopes.impl.toConeType
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
 import org.jetbrains.kotlin.fir.symbols.constructStarProjectedType
 import org.jetbrains.kotlin.fir.symbols.impl.*
-import org.jetbrains.kotlin.fir.types.ConeTypeProjection
+import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
-import org.jetbrains.kotlin.fir.types.classId
-import org.jetbrains.kotlin.fir.types.constructClassLikeType
-import org.jetbrains.kotlin.fir.types.toTypeProjection
 import org.jetbrains.kotlin.name.CallableId
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.Name
@@ -195,7 +192,7 @@ class SerializationFirResolveExtension(session: FirSession) : FirDeclarationGene
             valueParameters.addAll(List(serializableClassSymbol.typeParameterSymbols.size) { i ->
                 newSimpleValueParameter(
                     session,
-                    kSerializerClassId.constructClassLikeType(arrayOf(parametersAsArguments[i]), false).newRef(),
+                    kSerializerClassId.constructClassLikeType(arrayOf(parametersAsArguments[i]), false).toFirResolvedTypeRef(),
                     Name.identifier("${SerialEntityNames.typeArgPrefix}$i")
                 )
             })
@@ -267,7 +264,7 @@ class SerializationFirResolveExtension(session: FirSession) : FirDeclarationGene
                 valueParameters.addAll(owner.typeParameterSymbols.mapIndexed { i, typeParam ->
                     newSimpleValueParameter(
                         session,
-                        kSerializerClassId.constructClassLikeType(arrayOf(typeParam.toConeType()), false).newRef(),
+                        kSerializerClassId.constructClassLikeType(arrayOf(typeParam.toConeType()), false).toFirResolvedTypeRef(),
                         Name.identifier("${SerialEntityNames.typeArgPrefix}$i")
                     )
                 })
@@ -311,7 +308,7 @@ class SerializationFirResolveExtension(session: FirSession) : FirDeclarationGene
                         isNullable = false
                     )
                 ), isNullable = false
-            ).newRef()
+            ).toFirResolvedTypeRef()
         }
         return serializerFirClass.symbol
     }