diff --git a/compiler/tests/org/jetbrains/kotlin/serialization/DebugProtoBuf.java b/compiler/tests/org/jetbrains/kotlin/serialization/DebugProtoBuf.java
index d716ebcf5bb..316feefe7a7 100644
--- a/compiler/tests/org/jetbrains/kotlin/serialization/DebugProtoBuf.java
+++ b/compiler/tests/org/jetbrains/kotlin/serialization/DebugProtoBuf.java
@@ -10004,9 +10004,9 @@ public final class DebugProtoBuf {
        */
       CLASS(0, 0),
       /**
-       * <code>TRAIT = 1;</code>
+       * <code>INTERFACE = 1;</code>
        */
-      TRAIT(1, 1),
+      INTERFACE(1, 1),
       /**
        * <code>ENUM_CLASS = 2;</code>
        */
@@ -10024,7 +10024,7 @@ public final class DebugProtoBuf {
        */
       OBJECT(5, 5),
       /**
-       * <code>CLASS_OBJECT = 6;</code>
+       * <code>COMPANION_OBJECT = 6;</code>
        */
       CLASS_OBJECT(6, 6),
       ;
@@ -10038,9 +10038,9 @@ public final class DebugProtoBuf {
        */
       public static final int CLASS_VALUE = 0;
       /**
-       * <code>TRAIT = 1;</code>
+       * <code>INTERFACE = 1;</code>
        */
-      public static final int TRAIT_VALUE = 1;
+      public static final int INTERFACE_VALUE = 1;
       /**
        * <code>ENUM_CLASS = 2;</code>
        */
@@ -10058,7 +10058,7 @@ public final class DebugProtoBuf {
        */
       public static final int OBJECT_VALUE = 5;
       /**
-       * <code>CLASS_OBJECT = 6;</code>
+       * <code>COMPANION_OBJECT = 6;</code>
        */
       public static final int CLASS_OBJECT_VALUE = 6;
 
@@ -10068,7 +10068,7 @@ public final class DebugProtoBuf {
       public static Kind valueOf(int value) {
         switch (value) {
           case 0: return CLASS;
-          case 1: return TRAIT;
+          case 1: return INTERFACE;
           case 2: return ENUM_CLASS;
           case 3: return ENUM_ENTRY;
           case 4: return ANNOTATION_CLASS;
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 89a55a401be..68252b2a173 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
@@ -31,8 +31,7 @@ import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf.methodSignature
 import org.jetbrains.kotlin.serialization.jvm.JvmProtoBuf.propertySignature
 import org.jetbrains.kotlin.storage.StorageManager
 import org.jetbrains.kotlin.types.JetType
-import java.util.ArrayList
-import java.util.HashMap
+import java.util.*
 
 public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C : Any, T : Any>(
         storageManager: StorageManager,
@@ -203,11 +202,11 @@ public abstract class AbstractBinaryClassAnnotationAndConstantLoader<A : Any, C
         val classKind = Flags.CLASS_KIND[classProto.getFlags()]
         val classId = nameResolver.getClassId(classProto.getFqName())
 
-        if (classKind == ProtoBuf.Class.Kind.CLASS_OBJECT && isStaticFieldInOuter(proto) && seekForStaticFieldInOuter) {
+        if (classKind == ProtoBuf.Class.Kind.COMPANION_OBJECT && isStaticFieldInOuter(proto) && seekForStaticFieldInOuter) {
             // Backing fields of properties of a companion object are generated in the outer class
             return kotlinClassFinder.findKotlinClass(classId.getOuterClassId())
         }
-        else if (classKind == ProtoBuf.Class.Kind.TRAIT && (annotatedCallableKind == AnnotatedCallableKind.PROPERTY)) {
+        else if (classKind == ProtoBuf.Class.Kind.INTERFACE && (annotatedCallableKind == AnnotatedCallableKind.PROPERTY)) {
             if (proto.hasExtension(implClassName)) {
                 val parentPackageFqName = classId.getPackageFqName()
                 val tImplName = nameResolver.getName(proto.getExtension(implClassName))
diff --git a/core/deserialization/src/descriptors.proto b/core/deserialization/src/descriptors.proto
index 1d54045c109..5b242338ed0 100644
--- a/core/deserialization/src/descriptors.proto
+++ b/core/deserialization/src/descriptors.proto
@@ -171,12 +171,12 @@ message Class {
   enum Kind {
     // 3 bits
     CLASS = 0;
-    TRAIT = 1;
+    INTERFACE = 1;
     ENUM_CLASS = 2;
     ENUM_ENTRY = 3;
     ANNOTATION_CLASS = 4;
     OBJECT = 5;
-    CLASS_OBJECT = 6;
+    COMPANION_OBJECT = 6;
   }
 
   /*
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java b/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java
index 9ad679f1632..fad762391ad 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/Flags.java
@@ -87,13 +87,13 @@ public class Flags {
     }
 
     private static ProtoBuf.Class.Kind classKind(ClassKind kind, boolean isCompanionObject) {
-        if (isCompanionObject) return ProtoBuf.Class.Kind.CLASS_OBJECT;
+        if (isCompanionObject) return ProtoBuf.Class.Kind.COMPANION_OBJECT;
 
         switch (kind) {
             case CLASS:
                 return ProtoBuf.Class.Kind.CLASS;
             case INTERFACE:
-                return ProtoBuf.Class.Kind.TRAIT;
+                return ProtoBuf.Class.Kind.INTERFACE;
             case ENUM_CLASS:
                 return ProtoBuf.Class.Kind.ENUM_CLASS;
             case ENUM_ENTRY:
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/ProtoBuf.java b/core/deserialization/src/org/jetbrains/kotlin/serialization/ProtoBuf.java
index d792f2dc147..47b6350cf62 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/ProtoBuf.java
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/ProtoBuf.java
@@ -7937,9 +7937,9 @@ public final class ProtoBuf {
        */
       CLASS(0, 0),
       /**
-       * <code>TRAIT = 1;</code>
+       * <code>INTERFACE = 1;</code>
        */
-      TRAIT(1, 1),
+      INTERFACE(1, 1),
       /**
        * <code>ENUM_CLASS = 2;</code>
        */
@@ -7957,9 +7957,9 @@ public final class ProtoBuf {
        */
       OBJECT(5, 5),
       /**
-       * <code>CLASS_OBJECT = 6;</code>
+       * <code>COMPANION_OBJECT = 6;</code>
        */
-      CLASS_OBJECT(6, 6),
+      COMPANION_OBJECT(6, 6),
       ;
 
       /**
@@ -7971,9 +7971,9 @@ public final class ProtoBuf {
        */
       public static final int CLASS_VALUE = 0;
       /**
-       * <code>TRAIT = 1;</code>
+       * <code>INTERFACE = 1;</code>
        */
-      public static final int TRAIT_VALUE = 1;
+      public static final int INTERFACE_VALUE = 1;
       /**
        * <code>ENUM_CLASS = 2;</code>
        */
@@ -7991,9 +7991,9 @@ public final class ProtoBuf {
        */
       public static final int OBJECT_VALUE = 5;
       /**
-       * <code>CLASS_OBJECT = 6;</code>
+       * <code>COMPANION_OBJECT = 6;</code>
        */
-      public static final int CLASS_OBJECT_VALUE = 6;
+      public static final int COMPANION_OBJECT_VALUE = 6;
 
 
       public final int getNumber() { return value; }
@@ -8001,12 +8001,12 @@ public final class ProtoBuf {
       public static Kind valueOf(int value) {
         switch (value) {
           case 0: return CLASS;
-          case 1: return TRAIT;
+          case 1: return INTERFACE;
           case 2: return ENUM_CLASS;
           case 3: return ENUM_ENTRY;
           case 4: return ANNOTATION_CLASS;
           case 5: return OBJECT;
-          case 6: return CLASS_OBJECT;
+          case 6: return COMPANION_OBJECT;
           default: return null;
         }
       }
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 e62ad28f5b0..69eb7b6daeb 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
@@ -55,7 +55,7 @@ public class DeserializedClassDescriptor(
     private val visibility = Deserialization.visibility(Flags.VISIBILITY.get(classProto.getFlags()))
     private val kindFromProto = Flags.CLASS_KIND.get(classProto.getFlags())
     private val kind = Deserialization.classKind(kindFromProto)
-    private val isCompanion = kindFromProto == ProtoBuf.Class.Kind.CLASS_OBJECT
+    private val isCompanion = kindFromProto == ProtoBuf.Class.Kind.COMPANION_OBJECT
     private val isInner = Flags.INNER.get(classProto.getFlags())
 
     val c = outerContext.childContext(this, classProto.getTypeParameterList(), nameResolver)
diff --git a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt
index 97056542c05..8a08d44997b 100644
--- a/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt
+++ b/core/deserialization/src/org/jetbrains/kotlin/serialization/deserialization/protoEnumMapping.kt
@@ -16,11 +16,11 @@
 
 package org.jetbrains.kotlin.serialization.deserialization
 
-import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
-import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.serialization.ProtoBuf
 import org.jetbrains.kotlin.serialization.ProtoBuf.TypeParameter
 import org.jetbrains.kotlin.types.Variance
 
@@ -54,11 +54,11 @@ object Deserialization {
     @JvmStatic
     fun classKind(kind: ProtoBuf.Class.Kind): ClassKind = when (kind) {
         ProtoBuf.Class.Kind.CLASS -> ClassKind.CLASS
-        ProtoBuf.Class.Kind.TRAIT -> ClassKind.INTERFACE
+        ProtoBuf.Class.Kind.INTERFACE -> ClassKind.INTERFACE
         ProtoBuf.Class.Kind.ENUM_CLASS -> ClassKind.ENUM_CLASS
         ProtoBuf.Class.Kind.ENUM_ENTRY -> ClassKind.ENUM_ENTRY
         ProtoBuf.Class.Kind.ANNOTATION_CLASS -> ClassKind.ANNOTATION_CLASS
-        ProtoBuf.Class.Kind.OBJECT, ProtoBuf.Class.Kind.CLASS_OBJECT -> ClassKind.OBJECT
+        ProtoBuf.Class.Kind.OBJECT, ProtoBuf.Class.Kind.COMPANION_OBJECT -> ClassKind.OBJECT
     }
 
     @JvmStatic
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 6b21b477777..05789c31b1f 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
@@ -96,14 +96,14 @@ private class ClassClsStubBuilder(
         }
         val additionalModifiers = when (classKind) {
             ProtoBuf.Class.Kind.ENUM_CLASS -> listOf(JetTokens.ENUM_KEYWORD)
-            ProtoBuf.Class.Kind.CLASS_OBJECT -> listOf(JetTokens.COMPANION_KEYWORD)
+            ProtoBuf.Class.Kind.COMPANION_OBJECT -> listOf(JetTokens.COMPANION_KEYWORD)
             else -> listOf<JetModifierKeywordToken>()
         }
         return createModifierListStubForDeclaration(parent, classProto.getFlags(), relevantFlags, additionalModifiers)
     }
 
     private fun doCreateClassOrObjectStub(): StubElement<out PsiElement> {
-        val isCompanionObject = classKind == ProtoBuf.Class.Kind.CLASS_OBJECT
+        val isCompanionObject = classKind == ProtoBuf.Class.Kind.COMPANION_OBJECT
         val fqName = outerContext.containerFqName.child(classId.getShortClassName())
         val shortName = fqName.shortName().ref()
         val superTypeRefs = supertypeIds.filterNot {
@@ -111,7 +111,7 @@ private class ClassClsStubBuilder(
             KotlinBuiltIns.isNumberedFunctionClassFqName(it.asSingleFqName().toUnsafe())
         }.map { it.getShortClassName().ref() }.toTypedArray()
         return when (classKind) {
-            ProtoBuf.Class.Kind.OBJECT, ProtoBuf.Class.Kind.CLASS_OBJECT -> {
+            ProtoBuf.Class.Kind.OBJECT, ProtoBuf.Class.Kind.COMPANION_OBJECT -> {
                 KotlinObjectStubImpl(
                         parentStub, shortName, fqName, superTypeRefs,
                         isTopLevel = !classId.isNestedClass(),
@@ -127,7 +127,7 @@ private class ClassClsStubBuilder(
                         fqName.ref(),
                         shortName,
                         superTypeRefs,
-                        isTrait = classKind == ProtoBuf.Class.Kind.TRAIT,
+                        isTrait = classKind == ProtoBuf.Class.Kind.INTERFACE,
                         isEnumEntry = classKind == ProtoBuf.Class.Kind.ENUM_ENTRY,
                         isLocal = false,
                         isTopLevel = !classId.isNestedClass()