diff --git a/elastic4s-core/src/test/scala/com/sksamuel/elastic4s/requests/mappings/KnnVectorFieldTest.scala b/elastic4s-core/src/test/scala/com/sksamuel/elastic4s/requests/mappings/KnnVectorFieldTest.scala
index 1c9d4810e..35c044171 100644
--- a/elastic4s-core/src/test/scala/com/sksamuel/elastic4s/requests/mappings/KnnVectorFieldTest.scala
+++ b/elastic4s-core/src/test/scala/com/sksamuel/elastic4s/requests/mappings/KnnVectorFieldTest.scala
@@ -128,7 +128,7 @@ class KnnVectorFieldTest extends AnyFlatSpec with Matchers with ElasticApi {
         |"dimension":512,
         |"method":{"name":"hnsw","engine":"faiss","space_type":"l2",
         |"parameters":{"ef_construction":100,"m":50,"ef_search":50,
-        |"encoder":{"name":"pq","encoder":{"m":50,"code_size":100}}}}}""".stripMargin.replace(
+        |"encoder":{"name":"pq","parameters":{"m":50,"code_size":100}}}}}""".stripMargin.replace(
         "\n",
         ""
       )
@@ -161,7 +161,7 @@ class KnnVectorFieldTest extends AnyFlatSpec with Matchers with ElasticApi {
         |"dimension":512,
         |"method":{"name":"hnsw","engine":"faiss","space_type":"innerproduct",
         |"parameters":{"ef_construction":100,"m":50,"ef_search":50,
-        |"encoder":{"name":"sq","encoder":{"clip":true,"type":"fp16"}}}}}""".stripMargin.replace(
+        |"encoder":{"name":"sq","parameters":{"clip":true,"type":"fp16"}}}}}""".stripMargin.replace(
         "\n",
         ""
       )
@@ -182,12 +182,11 @@ class KnnVectorFieldTest extends AnyFlatSpec with Matchers with ElasticApi {
         KnnVectorField(
           name = "myfield123",
           dimension = 512,
-          HnswParameters(
+          IvfParameters(
             engine = Some(KnnEngine.faiss),
             spaceType = Some(SpaceType.innerProduct),
-            efConstruction = Some(100),
-            m = Some(50),
-            efSearch = Some(50),
+            nlist = Some(4),
+            nprobes = Some(2),
             encoder = Some(
               FaissEncoder(
                 Some(FaissEncoderName.sq),
@@ -201,9 +200,9 @@ class KnnVectorFieldTest extends AnyFlatSpec with Matchers with ElasticApi {
       .string shouldBe
       """{"type":"knn_vector",
         |"dimension":512,
-        |"method":{"name":"hnsw","engine":"faiss","space_type":"innerproduct",
-        |"parameters":{"ef_construction":100,"m":50,"ef_search":50,
-        |"encoder":{"name":"sq","encoder":{"clip":true,"type":"fp16"}}}}}""".stripMargin.replace(
+        |"method":{"name":"ivf","engine":"faiss","space_type":"innerproduct",
+        |"parameters":{"nlist":4,"nprobes":2,
+        |"encoder":{"name":"sq","parameters":{"clip":true,"type":"fp16"}}}}}""".stripMargin.replace(
         "\n",
         ""
       )
diff --git a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/fields/KnnVectorField.scala b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/fields/KnnVectorField.scala
index 039b8bbff..b4168d2f3 100644
--- a/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/fields/KnnVectorField.scala
+++ b/elastic4s-domain/src/main/scala/com/sksamuel/elastic4s/fields/KnnVectorField.scala
@@ -286,7 +286,7 @@ object IvfParameters {
       engine.get match {
         case KnnEngine.faiss =>
           // do nothing as all parameters are accepted
-          if (!encoder.isInstanceOf[FaissEncoder]) {
+          if (encoder.nonEmpty && !encoder.get.isInstanceOf[FaissEncoder]) {
             throw new IllegalArgumentException(
               "encoder must be instance of FaissEncoder for faiss engine"
             )
diff --git a/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/fields/KnnVectorFieldBuilderFn.scala b/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/fields/KnnVectorFieldBuilderFn.scala
index 1e0eb8c79..2cade8f77 100644
--- a/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/fields/KnnVectorFieldBuilderFn.scala
+++ b/elastic4s-handlers/src/main/scala/com/sksamuel/elastic4s/handlers/fields/KnnVectorFieldBuilderFn.scala
@@ -60,13 +60,35 @@ object KnnVectorFieldBuilderFn {
               .get("name")
               .map(_.asInstanceOf[String])
               .flatMap(v => FaissEncoderName.withName(v))
-            val m = e.get("m").map(_.asInstanceOf[Int])
-            val codeSize = e.get("code_size").map(_.asInstanceOf[Int])
-            val sqClip = e.get("clip").map(_.asInstanceOf[Boolean])
+            val m = e
+              .get("parameters")
+              .flatMap(p =>
+                p.asInstanceOf[Map[String, Any]]
+                  .get("m")
+                  .map(_.asInstanceOf[Int])
+              )
+            val codeSize = e
+              .get("parameters")
+              .flatMap(p =>
+                p.asInstanceOf[Map[String, Any]]
+                  .get("code_size")
+                  .map(_.asInstanceOf[Int])
+              )
+            val sqClip = e
+              .get("parameters")
+              .flatMap(p =>
+                p.asInstanceOf[Map[String, Any]]
+                  .get("clip")
+                  .map(_.asInstanceOf[Boolean])
+              )
             val sqType = e
-              .get("type")
-              .map(_.asInstanceOf[String])
-              .flatMap(v => FaissScalarQuantizationType.withName(v))
+              .get("parameters")
+              .flatMap(p =>
+                p.asInstanceOf[Map[String, Any]]
+                  .get("type")
+                  .map(_.asInstanceOf[String])
+                  flatMap (v => FaissScalarQuantizationType.withName(v))
+              )
             FaissEncoder(
               name = name,
               m = m,
@@ -152,7 +174,7 @@ object KnnVectorFieldBuilderFn {
           encoder.name.foreach(v => builder.field("name", v.name))
 
           // start of encoder `parameters` field
-          builder.startObject("encoder")
+          builder.startObject("parameters")
           encoder match {
             case e: FaissEncoder =>
               e.m.foreach(v => builder.field("m", v))
@@ -174,7 +196,7 @@ object KnnVectorFieldBuilderFn {
           encoder.name.foreach(v => builder.field("name", v.name))
 
           // start of encoder `parameters` field
-          builder.startObject("encoder")
+          builder.startObject("parameters")
           encoder match {
             case e: FaissEncoder =>
               e.m.foreach(v => builder.field("m", v))