diff --git a/java/vector/src/main/codegen/templates/AbstractPromotableFieldWriter.java b/java/vector/src/main/codegen/templates/AbstractPromotableFieldWriter.java
index 951edd5eeef..2e7792fcfe4 100644
--- a/java/vector/src/main/codegen/templates/AbstractPromotableFieldWriter.java
+++ b/java/vector/src/main/codegen/templates/AbstractPromotableFieldWriter.java
@@ -295,7 +295,7 @@ public MapWriter map(boolean keysSorted) {
 
   @Override
   public ExtensionWriter extension(ArrowType arrowType) {
-    return getWriter(MinorType.EXTENSIONTYPE).extension(arrowType);
+    return getWriter(MinorType.LIST).extension(arrowType);
   }
 
   @Override
@@ -325,7 +325,7 @@ public MapWriter map(String name, boolean keysSorted) {
 
   @Override
   public ExtensionWriter extension(String name, ArrowType arrowType) {
-    return getWriter(MinorType.EXTENSIONTYPE).extension(name, arrowType);
+    return getWriter(MinorType.STRUCT).extension(name, arrowType);
   }
 
   <#list vv.types as type><#list type.minor as minor>
diff --git a/java/vector/src/main/codegen/templates/UnionListWriter.java b/java/vector/src/main/codegen/templates/UnionListWriter.java
index d8a61cf1a60..1be6c0c5208 100644
--- a/java/vector/src/main/codegen/templates/UnionListWriter.java
+++ b/java/vector/src/main/codegen/templates/UnionListWriter.java
@@ -203,8 +203,7 @@ public MapWriter map(String name, boolean keysSorted) {
 
   @Override
   public ExtensionWriter extension(ArrowType arrowType) {
-    writer.extension(arrowType);
-    return writer;
+    return this;
   }
   
   @Override