diff --git a/build.gradle.kts b/build.gradle.kts
index a3ff210a85..d50d8a37fc 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -78,6 +78,9 @@ allprojects {
             }
         }
 
+        tasks.findByName("nativeTest")?.run {
+            outputs.upToDateWhen { false }
+        }
         tasks.findByName("jvmTest")?.run {
             outputs.upToDateWhen { false }
 
diff --git a/src/commonMain/kotlin/dev/evo/elasticmagic/Document.kt b/src/commonMain/kotlin/dev/evo/elasticmagic/Document.kt
index 707cf24883..eb175275ec 100644
--- a/src/commonMain/kotlin/dev/evo/elasticmagic/Document.kt
+++ b/src/commonMain/kotlin/dev/evo/elasticmagic/Document.kt
@@ -126,11 +126,16 @@ class BoundJoinField(
  */
 abstract class FieldSet : Named {
     private val fields: ArrayList<AnyField> = arrayListOf()
-    private val fieldsByName: HashMap<String, AnyField> = hashMapOf()
+    private val fieldsByName: HashMap<String, Int> = hashMapOf()
 
     internal fun addField(field: AnyField) {
-        fields.add(field)
-        fieldsByName[field.getFieldName()] = field
+        val existingFieldIx = fieldsByName[field.getFieldName()]
+        if (existingFieldIx != null) {
+            fields[existingFieldIx] = field
+        } else {
+            fieldsByName[field.getFieldName()] = fields.size
+            fields.add(field)
+        }
     }
 
     internal fun getAllFields(): List<AnyField> {
@@ -138,7 +143,7 @@ abstract class FieldSet : Named {
     }
 
     internal fun getFieldByName(name: String): AnyField? {
-        return fieldsByName[name]
+        return fields[fieldsByName[name] ?: return null]
     }
 
     fun <T> field(