diff --git a/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/util.kt b/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/util.kt
index 706fabd4f2e..5a610f0d868 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/util.kt
+++ b/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/descriptors/util.kt
@@ -21,12 +21,11 @@ import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.descriptors.impl.ValueParameterDescriptorImpl
 import org.jetbrains.kotlin.load.java.lazy.descriptors.LazyJavaStaticClassScope
+import org.jetbrains.kotlin.load.kotlin.JvmPackagePartSource
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.descriptorUtil.getSuperClassNotAny
 import org.jetbrains.kotlin.resolve.descriptorUtil.module
-import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.DeserializedCallableMemberDescriptor
-import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf
 import org.jetbrains.kotlin.types.KotlinType
 
 fun copyValueParameters(
@@ -34,7 +33,7 @@ fun copyValueParameters(
         oldValueParameters: Collection<ValueParameterDescriptor>,
         newOwner: CallableDescriptor
 ): List<ValueParameterDescriptor> {
-    assert(newValueParametersTypes.size() == oldValueParameters.size()) {
+    assert(newValueParametersTypes.size == oldValueParameters.size) {
         "Different value parameters sizes: Enhanced = ${newValueParametersTypes.size}, Old = ${oldValueParameters.size}"
     }
 
@@ -45,14 +44,14 @@ fun copyValueParameters(
                 newOwner,
                 oldParameter,
                 oldParameter.index,
-                oldParameter.getAnnotations(),
-                oldParameter.getName(),
+                oldParameter.annotations,
+                oldParameter.name,
                 newType,
                 oldParameter.declaresDefaultValue(),
                 oldParameter.isCrossinline,
                 oldParameter.isNoinline,
                 if (oldParameter.varargElementType != null) newOwner.module.builtIns.getArrayElementType(newType) else null,
-                oldParameter.getSource()
+                oldParameter.source
         )
     }
 }
@@ -68,19 +67,5 @@ fun ClassDescriptor.getParentJavaStaticClassScope(): LazyJavaStaticClassScope? {
 }
 
 fun DeserializedCallableMemberDescriptor.getImplClassNameForDeserialized(): Name? {
-    val proto = proto
-    return when (proto) {
-        is ProtoBuf.Constructor ->
-            null
-        is ProtoBuf.Function ->
-            if (proto.hasExtension(JvmProtoBuf.methodImplClassName))
-                proto.getExtension(JvmProtoBuf.methodImplClassName)
-            else null
-        is ProtoBuf.Property ->
-            if (proto.hasExtension(JvmProtoBuf.propertyImplClassName))
-                proto.getExtension(JvmProtoBuf.propertyImplClassName)
-            else null
-        else ->
-            error("Unknown message: $proto")
-    }?.let { nameResolver.getName(it) }
+    return (packagePartSource as? JvmPackagePartSource)?.className?.fqNameForClassNameWithoutDollars?.shortName()
 }
diff --git a/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/AbstractBinaryClassAnnotationAndConstantLoader.kt b/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/AbstractBinaryClassAnnotationAndConstantLoader.kt
index f2e2c82a02a..24ecab7e72b 100644
--- a/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/AbstractBinaryClassAnnotationAndConstantLoader.kt
+++ b/core/descriptor.loader.java/src/org/jetbrains/kotlin/load/kotlin/AbstractBinaryClassAnnotationAndConstantLoader.kt
@@ -21,13 +21,13 @@ import org.jetbrains.kotlin.descriptors.SourceElement
 import org.jetbrains.kotlin.load.java.JvmAbi
 import org.jetbrains.kotlin.load.java.JvmAnnotationNames
 import org.jetbrains.kotlin.name.ClassId
-import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.serialization.deserialization.*
 import org.jetbrains.kotlin.serialization.jvm.ClassMapperLite
 import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf
-import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf.*
+import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf.index
+import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf.propertySignature
 import org.jetbrains.kotlin.serialization.jvm.JvmProtoBufUtil
 import org.jetbrains.kotlin.storage.StorageManager
 import org.jetbrains.kotlin.types.KotlinType
@@ -95,26 +95,26 @@ public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C
             val fieldSignature = getPropertySignature(proto, container.nameResolver, container.typeTable, field = true)
 
             val propertyAnnotations = syntheticFunctionSignature?.let { sig ->
-                findClassAndLoadMemberAnnotations(container, proto, sig)
+                findClassAndLoadMemberAnnotations(container, sig, property = true)
             }.orEmpty()
 
             val fieldAnnotations = fieldSignature?.let { sig ->
-                findClassAndLoadMemberAnnotations(container, proto, sig, field = true)
+                findClassAndLoadMemberAnnotations(container, sig, property = true, field = true)
             }.orEmpty()
 
             return loadPropertyAnnotations(propertyAnnotations, fieldAnnotations)
         }
 
         val signature = getCallableSignature(proto, container.nameResolver, container.typeTable, kind) ?: return emptyList()
-        return transformAnnotations(findClassAndLoadMemberAnnotations(container, proto, signature))
+        return transformAnnotations(findClassAndLoadMemberAnnotations(container, signature))
     }
 
     override fun loadEnumEntryAnnotations(container: ProtoContainer, proto: ProtoBuf.EnumEntry): List<A> {
         val signature = MemberSignature.fromFieldNameAndDesc(
                 container.nameResolver.getString(proto.name),
-                ClassMapperLite.mapClass(container.nameResolver.getClassId((container as ProtoContainer.Class).classProto.fqName))
+                ClassMapperLite.mapClass((container as ProtoContainer.Class).classId)
         )
-        return findClassAndLoadMemberAnnotations(container, proto, signature)
+        return findClassAndLoadMemberAnnotations(container, signature)
     }
 
     protected abstract fun loadPropertyAnnotations(propertyAnnotations: List<A>, fieldAnnotations: List<A>): List<T>
@@ -122,13 +122,10 @@ public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C
     protected abstract fun transformAnnotations(annotations: List<A>): List<T>
 
     private fun findClassAndLoadMemberAnnotations(
-            container: ProtoContainer, proto: MessageLite, signature: MemberSignature, field: Boolean = false
+            container: ProtoContainer, signature: MemberSignature, property: Boolean = false, field: Boolean = false
     ): List<A> {
-        val kotlinClass = findClassWithAnnotationsAndInitializers(container, getImplClassName(proto, container.nameResolver), field)
-        if (kotlinClass == null) {
-            errorReporter.reportLoadingError("Kotlin class for loading member annotations is not found: ${container.debugFqName()}", null)
-            return listOf()
-        }
+        val kotlinClass = findClassWithAnnotationsAndInitializers(container, getImplClassName(container, property), field)
+                          ?: return listOf()
 
         return storage(kotlinClass).memberAnnotations[signature] ?: listOf()
     }
@@ -144,7 +141,7 @@ public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C
         if (methodSignature != null) {
             val index = if (proto.hasExtension(index)) proto.getExtension(index) else parameterIndex
             val paramSignature = MemberSignature.fromMethodSignatureAndParameterIndex(methodSignature, index)
-            return findClassAndLoadMemberAnnotations(container, message, paramSignature)
+            return findClassAndLoadMemberAnnotations(container, paramSignature)
         }
 
         return listOf()
@@ -158,7 +155,7 @@ public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C
         val methodSignature = getCallableSignature(message, container.nameResolver, container.typeTable, kind)
         if (methodSignature != null) {
             val paramSignature = MemberSignature.fromMethodSignatureAndParameterIndex(methodSignature, 0)
-            return findClassAndLoadMemberAnnotations(container, message, paramSignature)
+            return findClassAndLoadMemberAnnotations(container, paramSignature)
         }
 
         return emptyList()
@@ -173,54 +170,41 @@ public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C
     }
 
     override fun loadPropertyConstant(container: ProtoContainer, proto: ProtoBuf.Property, expectedType: KotlinType): C? {
-        val nameResolver = container.nameResolver
-        val signature = getCallableSignature(proto, nameResolver, container.typeTable, AnnotatedCallableKind.PROPERTY) ?: return null
+        val signature = getCallableSignature(proto, container.nameResolver, container.typeTable, AnnotatedCallableKind.PROPERTY)
+                        ?: return null
 
-        val kotlinClass = findClassWithAnnotationsAndInitializers(container, getImplClassName(proto, nameResolver), field = true)
-        if (kotlinClass == null) {
-            errorReporter.reportLoadingError("Kotlin class for loading property constant is not found: ${container.debugFqName()}", null)
-            return null
-        }
+        val kotlinClass = findClassWithAnnotationsAndInitializers(container, getImplClassName(container, property = true), field = true)
+                          ?: return null
 
         return storage(kotlinClass).propertyConstants[signature]
     }
 
     private fun findClassWithAnnotationsAndInitializers(
-            container: ProtoContainer, implClassName: Name?, field: Boolean
-    ): KotlinJvmBinaryClass? = when (container) {
-        is ProtoContainer.Package -> {
-            implClassName?.let { kotlinClassFinder.findKotlinClass(ClassId(container.fqName, it)) }
+            container: ProtoContainer, implClassName: ClassId?, field: Boolean
+    ): KotlinJvmBinaryClass? {
+        if (implClassName != null) {
+            return kotlinClassFinder.findKotlinClass(implClassName)
         }
-        is ProtoContainer.Class -> {
-            val classId = container.nameResolver.getClassId(container.classProto.fqName)
 
-            if (implClassName != null) {
-                // TODO: store accurate name for nested traits
-                val implClassId =
-                    if (implClassName.asString().endsWith(JvmAbi.DEFAULT_IMPLS_SUFFIX))
-                        ClassId(classId.packageFqName, FqName(implClassName.asString().replace(JvmAbi.DEFAULT_IMPLS_SUFFIX, "." + JvmAbi.DEFAULT_IMPLS_CLASS_NAME)), false)
-                    else
-                        ClassId(classId.packageFqName, implClassName)
-                kotlinClassFinder.findKotlinClass(implClassId)
-            }
-            else if (field && container.isCompanionOfClass) {
+        if (container is ProtoContainer.Class) {
+            if (field && container.isCompanionOfClass) {
                 // Backing fields of properties of a companion object in a class are generated in the outer class
-                kotlinClassFinder.findKotlinClass(classId.outerClassId)
-            }
-            else {
-                kotlinClassFinder.findKotlinClass(classId)
+                return kotlinClassFinder.findKotlinClass(container.classId.outerClassId)
             }
+
+            return kotlinClassFinder.findKotlinClass(container.classId)
         }
+
+        return null
     }
 
-    private fun getImplClassName(proto: MessageLite, nameResolver: NameResolver): Name? =
-            when {
-                proto is ProtoBuf.Function && proto.hasExtension(methodImplClassName) ->
-                    nameResolver.getName(proto.getExtension(methodImplClassName))
-                proto is ProtoBuf.Property && proto.hasExtension(propertyImplClassName) ->
-                    nameResolver.getName(proto.getExtension(propertyImplClassName))
-                else -> null
-            }
+    private fun getImplClassName(container: ProtoContainer, property: Boolean): ClassId? {
+        if (property && container is ProtoContainer.Class && container.isInterface) {
+            return container.classId.createNestedClassId(Name.identifier(JvmAbi.DEFAULT_IMPLS_CLASS_NAME))
+        }
+        return ((container as? ProtoContainer.Package)?.packagePartSource as? JvmPackagePartSource)
+                ?.className?.fqNameForClassNameWithoutDollars?.let { ClassId.topLevel(it) }
+    }
 
     private fun loadAnnotationsAndInitializers(kotlinClass: KotlinJvmBinaryClass): Storage<A, C> {
         val memberAnnotations = HashMap<MemberSignature, MutableList<A>>()
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/MemberDeserializer.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/MemberDeserializer.kt
index feff5369c51..49ef944bbe9 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/MemberDeserializer.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/MemberDeserializer.kt
@@ -248,7 +248,8 @@ public class MemberDeserializer(private val c: DeserializationContext) {
         is DeserializedClassDescriptor -> ProtoContainer.Class(
                 classProto, c.nameResolver, c.typeTable,
                 isCompanionOfClass = DescriptorUtils.isCompanionObject(this) &&
-                                     containingDeclaration.let { DescriptorUtils.isClass(it) || DescriptorUtils.isEnumClass(it) }
+                                     containingDeclaration.let { DescriptorUtils.isClass(it) || DescriptorUtils.isEnumClass(it) },
+                isInterface = kind == ClassKind.INTERFACE
         )
         else -> null // TODO: support annotations on lambdas and their parameters
     }
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/ProtoContainer.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/ProtoContainer.kt
index 1050da9ca79..bb6908c3371 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/ProtoContainer.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/ProtoContainer.kt
@@ -16,6 +16,7 @@
 
 package org.jetbrains.kotlin.serialization.deserialization
 
+import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.serialization.deserialization.descriptors.PackagePartSource
@@ -28,9 +29,12 @@ sealed class ProtoContainer(
             val classProto: ProtoBuf.Class,
             nameResolver: NameResolver,
             typeTable: TypeTable,
-            val isCompanionOfClass: Boolean
+            val isCompanionOfClass: Boolean,
+            val isInterface: Boolean
     ) : ProtoContainer(nameResolver, typeTable) {
-        override fun debugFqName(): FqName = nameResolver.getClassId(classProto.fqName).asSingleFqName()
+        val classId: ClassId = nameResolver.getClassId(classProto.fqName)
+
+        override fun debugFqName(): FqName = classId.asSingleFqName()
     }
 
     class Package(
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/descriptors/DeserializedClassDescriptor.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/descriptors/DeserializedClassDescriptor.kt
index 77b659b9a40..775a81e1531 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/descriptors/DeserializedClassDescriptor.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/descriptors/DeserializedClassDescriptor.kt
@@ -296,7 +296,8 @@ public class DeserializedClassDescriptor(
             val annotations = enumEntryProtos[name]?.let { proto ->
                 DeserializedAnnotations(c.storageManager) {
                     c.components.annotationAndConstantLoader.loadEnumEntryAnnotations(
-                            ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass = false), proto
+                            ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass = false, isInterface = false),
+                            proto
                     )
                 }
             } ?: if (name in oldEnumEntryNames) Annotations.EMPTY
diff --git a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/stubBuilder/ClassClsStubBuilder.kt b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/stubBuilder/ClassClsStubBuilder.kt
index 4c48a53dc90..844837db89e 100644
--- a/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/stubBuilder/ClassClsStubBuilder.kt
+++ b/idea/idea-analysis/src/org/jetbrains/kotlin/idea/decompiler/stubBuilder/ClassClsStubBuilder.kt
@@ -68,6 +68,7 @@ private class ClassClsStubBuilder(
         return classKind == ProtoBuf.Class.Kind.COMPANION_OBJECT &&
                (outerContext.classKind?.let { it == ProtoBuf.Class.Kind.CLASS || it == ProtoBuf.Class.Kind.ENUM_CLASS } ?: false)
     }
+    private val isInterface: Boolean get() = classKind == ProtoBuf.Class.Kind.INTERFACE
 
     private val classOrObjectStub = createClassOrObjectStubAndModifierListStub()
 
@@ -142,7 +143,7 @@ private class ClassClsStubBuilder(
         val primaryConstructorProto = classProto.constructorList.find { !Flags.IS_SECONDARY.get(it.flags) } ?: return
 
         createConstructorStub(classOrObjectStub, primaryConstructorProto, c,
-                              ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass))
+                              ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass, isInterface))
     }
 
     private fun createDelegationSpecifierList() {
@@ -180,7 +181,7 @@ private class ClassClsStubBuilder(
     private fun createEnumEntryStubs(classBody: KotlinPlaceHolderStubImpl<KtClassBody>) {
         if (classKind != ProtoBuf.Class.Kind.ENUM_CLASS) return
 
-        val container = ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass = false)
+        val container = ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass, isInterface)
         val enumEntries: List<Pair<Int, List<ClassId>>> =
                 if (classProto.enumEntryList.isNotEmpty())
                     classProto.enumEntryList.map { enumEntryProto ->
@@ -211,7 +212,7 @@ private class ClassClsStubBuilder(
     }
 
     private fun createCallableMemberStubs(classBody: KotlinPlaceHolderStubImpl<KtClassBody>) {
-        val container = ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass)
+        val container = ProtoContainer.Class(classProto, c.nameResolver, c.typeTable, isCompanionOfClass, isInterface)
 
         for (secondaryConstructorProto in classProto.constructorList) {
             if (Flags.IS_SECONDARY.get(secondaryConstructorProto.flags)) {