diff --git a/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/diagnostics/SerializableEnums.txt b/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/diagnostics/SerializableEnums.txt
index 8f427ca065c..5e912f7da27 100644
--- a/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/diagnostics/SerializableEnums.txt
+++ b/plugins/kotlin-serialization/kotlin-serialization-compiler/testData/diagnostics/SerializableEnums.txt
@@ -103,6 +103,14 @@ public object EnumSerializer : kotlinx.serialization.KSerializer<ExplicitlyMarke
     public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
+    public companion object Companion {
+        private constructor Companion()
+        public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public final /*synthesized*/ fun serializer(): kotlinx.serialization.KSerializer<ExplicitlyMarkedEnumCustom>
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
     // Static members
     public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): ExplicitlyMarkedEnumCustom
     public final /*synthesized*/ fun values(): kotlin.Array<ExplicitlyMarkedEnumCustom>