diff --git a/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializableIrGenerator.kt b/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializableIrGenerator.kt
index e76b50f3c22..7db4fd082b4 100644
--- a/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializableIrGenerator.kt
+++ b/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializableIrGenerator.kt
@@ -369,6 +369,7 @@ class SerializableIrGenerator(
         val serializerDescriptor = irClass.classSerializer(compilerContext)?.owner ?: return
         if (irClass.shouldHaveSpecificSyntheticMethods { serializerDescriptor.findPluginGeneratedMethod(SAVE) }) {
             val func = irClass.findWriteSelfMethod() ?: return
+            func.origin = SERIALIZATION_PLUGIN_ORIGIN
             generateWriteSelfMethod(func)
         }
     }
diff --git a/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializerIrGenerator.kt b/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializerIrGenerator.kt
index 87fa34d2fbc..618e4b42225 100644
--- a/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializerIrGenerator.kt
+++ b/plugins/kotlinx-serialization/kotlinx-serialization.backend/src/org/jetbrains/kotlinx/serialization/compiler/backend/ir/SerializerIrGenerator.kt
@@ -623,6 +623,7 @@ open class SerializerIrGenerator(
                 else -> SerializerIrGenerator(irClass, context, metadataPlugin)
             }
             generator.generate()
+            irClass.origin = SERIALIZATION_PLUGIN_ORIGIN
             irClass.addDefaultConstructorIfAbsent(context)
             irClass.patchDeclarationParents(irClass.parent)
         }
diff --git a/plugins/kotlinx-serialization/testData/codegen/Basic.asm.ir.txt b/plugins/kotlinx-serialization/testData/codegen/Basic.asm.ir.txt
index b8fb050138d..b67e14de703 100644
--- a/plugins/kotlinx-serialization/testData/codegen/Basic.asm.ir.txt
+++ b/plugins/kotlinx-serialization/testData/codegen/Basic.asm.ir.txt
@@ -295,16 +295,6 @@ public final class ListOfUsers : java/lang/Object {
 
     public final static void write$Self(ListOfUsers self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
-          ALOAD (0)
-          LDC (self)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (1)
-          LDC (output)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (2)
-          LDC (serialDesc)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-        LABEL (L1)
         LINENUMBER (12)
           ALOAD (1)
           ALOAD (2)
@@ -319,7 +309,7 @@ public final class ListOfUsers : java/lang/Object {
           GETFIELD (ListOfUsers, list, Ljava/util/List;)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, encodeSerializableElement, (Lkotlinx/serialization/descriptors/SerialDescriptor;ILkotlinx/serialization/SerializationStrategy;Ljava/lang/Object;)V)
           RETURN
-        LABEL (L2)
+        LABEL (L1)
     }
 }
 
@@ -656,28 +646,18 @@ public final class OptionalUser : java/lang/Object {
 
     public final static void write$Self(OptionalUser self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
-          ALOAD (0)
-          LDC (self)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (1)
-          LDC (output)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (2)
-          LDC (serialDesc)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-        LABEL (L1)
         LINENUMBER (9)
           ALOAD (1)
           ALOAD (2)
           ICONST_0
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, shouldEncodeElementDefault, (Lkotlinx/serialization/descriptors/SerialDescriptor;I)Z)
-          IFEQ (L2)
+          IFEQ (L1)
           ICONST_1
-          GOTO (L3)
-        LABEL (L2)
+          GOTO (L2)
+        LABEL (L1)
           ALOAD (0)
           GETFIELD (OptionalUser, user, LUser;)
-        LABEL (L4)
+        LABEL (L3)
         LINENUMBER (10)
           NEW (User)
           DUP
@@ -685,14 +665,14 @@ public final class OptionalUser : java/lang/Object {
           LDC ()
           INVOKESPECIAL (User, <init>, (Ljava/lang/String;Ljava/lang/String;)V)
           INVOKESTATIC (kotlin/jvm/internal/Intrinsics, areEqual, (Ljava/lang/Object;Ljava/lang/Object;)Z)
-          IFNE (L5)
+          IFNE (L4)
           ICONST_1
-          GOTO (L3)
-        LABEL (L5)
+          GOTO (L2)
+        LABEL (L4)
           ICONST_0
-        LABEL (L3)
-          IFEQ (L6)
-        LABEL (L7)
+        LABEL (L2)
+          IFEQ (L5)
+        LABEL (L6)
         LINENUMBER (9)
           ALOAD (1)
           ALOAD (2)
@@ -702,9 +682,9 @@ public final class OptionalUser : java/lang/Object {
           ALOAD (0)
           GETFIELD (OptionalUser, user, LUser;)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, encodeSerializableElement, (Lkotlinx/serialization/descriptors/SerialDescriptor;ILkotlinx/serialization/SerializationStrategy;Ljava/lang/Object;)V)
-        LABEL (L6)
+        LABEL (L5)
           RETURN
-        LABEL (L8)
+        LABEL (L7)
     }
 }
 
@@ -1032,16 +1012,6 @@ public final class User : java/lang/Object {
 
     public final static void write$Self(User self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
-          ALOAD (0)
-          LDC (self)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (1)
-          LDC (output)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (2)
-          LDC (serialDesc)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-        LABEL (L1)
         LINENUMBER (6)
           ALOAD (1)
           ALOAD (2)
@@ -1056,6 +1026,6 @@ public final class User : java/lang/Object {
           GETFIELD (User, lastName, Ljava/lang/String;)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, encodeStringElement, (Lkotlinx/serialization/descriptors/SerialDescriptor;ILjava/lang/String;)V)
           RETURN
-        LABEL (L2)
+        LABEL (L1)
     }
 }
diff --git a/plugins/kotlinx-serialization/testData/codegen/Sealed.asm.ir.txt b/plugins/kotlinx-serialization/testData/codegen/Sealed.asm.ir.txt
index b897cf03d40..04c55809c0b 100644
--- a/plugins/kotlinx-serialization/testData/codegen/Sealed.asm.ir.txt
+++ b/plugins/kotlinx-serialization/testData/codegen/Sealed.asm.ir.txt
@@ -249,16 +249,6 @@ public final class Container : java/lang/Object {
 
     public final static void write$Self(Container self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
-          ALOAD (0)
-          LDC (self)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (1)
-          LDC (output)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (2)
-          LDC (serialDesc)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-        LABEL (L1)
         LINENUMBER (18)
           ALOAD (1)
           ALOAD (2)
@@ -270,7 +260,7 @@ public final class Container : java/lang/Object {
           GETFIELD (Container, r, LResult;)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, encodeSerializableElement, (Lkotlinx/serialization/descriptors/SerialDescriptor;ILkotlinx/serialization/SerializationStrategy;Ljava/lang/Object;)V)
           RETURN
-        LABEL (L2)
+        LABEL (L1)
     }
 }
 
@@ -716,16 +706,6 @@ public final class Result$OK : Result {
 
     public final static void write$Self(Result$OK self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
-          ALOAD (0)
-          LDC (self)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (1)
-          LDC (output)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (2)
-          LDC (serialDesc)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-        LABEL (L1)
         LINENUMBER (14)
           ALOAD (0)
           CHECKCAST (Result)
@@ -739,7 +719,7 @@ public final class Result$OK : Result {
           GETFIELD (Result$OK, s, Ljava/lang/String;)
           INVOKEINTERFACE (kotlinx/serialization/encoding/CompositeEncoder, encodeStringElement, (Lkotlinx/serialization/descriptors/SerialDescriptor;ILjava/lang/String;)V)
           RETURN
-        LABEL (L2)
+        LABEL (L1)
     }
 }
 
@@ -798,15 +778,6 @@ public abstract class Result : java/lang/Object, X {
 
     public final static void write$Self(Result self, kotlinx.serialization.encoding.CompositeEncoder output, kotlinx.serialization.descriptors.SerialDescriptor serialDesc) {
         LABEL (L0)
-          ALOAD (0)
-          LDC (self)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (1)
-          LDC (output)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
-          ALOAD (2)
-          LDC (serialDesc)
-          INVOKESTATIC (kotlin/jvm/internal/Intrinsics, checkNotNullParameter, (Ljava/lang/Object;Ljava/lang/String;)V)
           RETURN
         LABEL (L1)
     }