diff --git a/nusamai/src/sink/mvt/mod.rs b/nusamai/src/sink/mvt/mod.rs
index 76040f8e..7457041e 100644
--- a/nusamai/src/sink/mvt/mod.rs
+++ b/nusamai/src/sink/mvt/mod.rs
@@ -433,14 +433,12 @@ fn make_tile(default_detail: i32, serialized_feats: &[Vec<u8>]) -> Result<Vec<u8
         }
 
         let mut id = None;
-        let mut tags: Vec<u32> = Vec::new();
-
         let layer = if let object::Value::Object(obj) = &feature.properties {
             let layer = layers.entry_ref(obj.typename.as_ref()).or_default();
 
             // Encode attributes as MVT tags
             for (key, value) in &obj.attributes {
-                convert_properties(&mut tags, &mut layer.tags_enc, key, value);
+                convert_properties(&mut layer.tags_enc, key, value);
             }
 
             // Make a MVT feature id (u64) by hashing the original feature id string.
@@ -457,7 +455,7 @@ fn make_tile(default_detail: i32, serialized_feats: &[Vec<u8>]) -> Result<Vec<u8
 
         layer.features.push(vector_tile::tile::Feature {
             id,
-            tags,
+            tags: layer.tags_enc.flush_tags(),
             r#type: Some(vector_tile::tile::GeomType::Polygon as i32),
             geometry,
         });
diff --git a/nusamai/src/sink/mvt/tags.rs b/nusamai/src/sink/mvt/tags.rs
index 0a3be2af..bb8581a3 100644
--- a/nusamai/src/sink/mvt/tags.rs
+++ b/nusamai/src/sink/mvt/tags.rs
@@ -1,42 +1,37 @@
 use nusamai_citygml::object;
 use tinymvt::tag::TagsEncoder;
 
-pub fn convert_properties(
-    tags: &mut Vec<u32>,
-    tags_enc: &mut TagsEncoder,
-    name: &str,
-    tree: &object::Value,
-) {
+pub fn convert_properties(tags_enc: &mut TagsEncoder, name: &str, tree: &object::Value) {
     match &tree {
         nusamai_citygml::Value::String(v) => {
-            tags.extend(tags_enc.add(name, v.clone().into()));
+            tags_enc.add(name, v.clone().into());
         }
         nusamai_citygml::Value::Code(v) => {
-            tags.extend(tags_enc.add(name, v.value().into()));
+            tags_enc.add(name, v.value().into());
         }
         nusamai_citygml::Value::Integer(v) => {
-            tags.extend(tags_enc.add(name, (*v).into()));
+            tags_enc.add(name, (*v).into());
         }
         nusamai_citygml::Value::NonNegativeInteger(v) => {
-            tags.extend(tags_enc.add(name, (*v).into()));
+            tags_enc.add(name, (*v).into());
         }
         nusamai_citygml::Value::Double(v) => {
-            tags.extend(tags_enc.add(name, (*v).into()));
+            tags_enc.add(name, (*v).into());
         }
         nusamai_citygml::Value::Measure(v) => {
-            tags.extend(tags_enc.add(name, v.value().into()));
+            tags_enc.add(name, v.value().into());
         }
         nusamai_citygml::Value::Boolean(v) => {
-            tags.extend(tags_enc.add(name, (*v).into()));
+            tags_enc.add(name, (*v).into());
         }
         nusamai_citygml::Value::Uri(v) => {
-            tags.extend(tags_enc.add(name, v.value().to_string().into()));
+            tags_enc.add(name, v.value().to_string().into());
         }
         nusamai_citygml::Value::Date(v) => {
-            tags.extend(tags_enc.add(name, v.to_string().into()));
+            tags_enc.add(name, v.to_string().into());
         }
         nusamai_citygml::Value::Point(v) => {
-            tags.extend(tags_enc.add(name, format!("{:?}", v).into())); // FIXME
+            tags_enc.add(name, format!("{:?}", v).into()); // FIXME
         }
         nusamai_citygml::Value::Array(_arr) => {
             // ignore non-root attributes