diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/MlLTRNamedXContentProvider.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/MlLTRNamedXContentProvider.java
index 6f78077e16288..b878aad27a42e 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/MlLTRNamedXContentProvider.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/MlLTRNamedXContentProvider.java
@@ -9,6 +9,7 @@
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.plugins.spi.NamedXContentProvider;
 import org.elasticsearch.xcontent.NamedXContentRegistry;
+import org.elasticsearch.xpack.core.ml.inference.trainedmodel.InferenceConfig;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.LearnToRankConfig;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.LenientlyParsedInferenceConfig;
 import org.elasticsearch.xpack.core.ml.inference.trainedmodel.StrictlyParsedInferenceConfig;
@@ -58,7 +59,7 @@ public List<NamedWriteableRegistry.Entry> getNamedWriteables() {
         List<NamedWriteableRegistry.Entry> namedWriteables = new ArrayList<>();
         // Inference config
         namedWriteables.add(
-            new NamedWriteableRegistry.Entry(LearnToRankConfig.class, LearnToRankConfig.NAME.getPreferredName(), LearnToRankConfig::new)
+            new NamedWriteableRegistry.Entry(InferenceConfig.class, LearnToRankConfig.NAME.getPreferredName(), LearnToRankConfig::new)
         );
         // LTR Extractors
         namedWriteables.add(
diff --git a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/ltr/LearnToRankRescorerBuilder.java b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/ltr/LearnToRankRescorerBuilder.java
index 4f50751abb972..dfd96dbb27bbc 100644
--- a/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/ltr/LearnToRankRescorerBuilder.java
+++ b/x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/ltr/LearnToRankRescorerBuilder.java
@@ -89,7 +89,11 @@ public LearnToRankRescorerBuilder(StreamInput input, LearnToRankService learnToR
         super(input);
         this.modelId = input.readString();
         this.params = input.readMap();
-        this.learnToRankConfig = input.readOptionalNamedWriteable(LearnToRankConfig.class);
+        if (input.readBoolean()) {
+            this.learnToRankConfig = new LearnToRankConfig(input);
+        } else {
+            this.learnToRankConfig = null;
+        }
         this.learnToRankService = learnToRankService;
 
         this.localModel = null;
@@ -254,7 +258,13 @@ protected void doWriteTo(StreamOutput out) throws IOException {
         assert localModel == null || rescoreOccurred : "Unnecessarily populated local model object";
         out.writeString(modelId);
         out.writeGenericMap(params);
-        out.writeOptionalNamedWriteable(learnToRankConfig);
+
+        if (learnToRankConfig != null) {
+            out.writeBoolean(true);
+            learnToRankConfig.writeTo(out);
+        } else {
+            out.writeBoolean(false);
+        }
     }
 
     @Override