diff --git a/src/compose/compose-collection.ts b/src/compose/compose-collection.ts
index 3c21b44d..a287bf1a 100644
--- a/src/compose/compose-collection.ts
+++ b/src/compose/compose-collection.ts
@@ -38,10 +38,8 @@ function resolveCollection(
   if (tagName === '!' || tagName === Coll.tagName) {
     coll.tag = Coll.tagName
     return coll
-  } else if (tagName) {
-    coll.tag = tagName
   }
-
+  if (tagName) coll.tag = tagName
   return coll
 }
 
@@ -58,7 +56,6 @@ export function composeCollection(
         onError(tagToken, 'TAG_RESOLVE_FAILED', msg)
       )
 
-  let coll: YAMLMap.Parsed | YAMLSeq.Parsed
   let expType: 'map' | 'seq' | undefined =
     token.type === 'block-map'
       ? 'map'
@@ -133,7 +130,7 @@ export function composeCollection(
     }
   }
 
-  coll = resolveCollection(CN, ctx, token, onError, tagName, tag)
+  const coll = resolveCollection(CN, ctx, token, onError, tagName, tag)
 
   const res =
     tag.resolve?.(
diff --git a/src/compose/resolve-flow-collection.ts b/src/compose/resolve-flow-collection.ts
index 10377ac9..33f7b2ba 100644
--- a/src/compose/resolve-flow-collection.ts
+++ b/src/compose/resolve-flow-collection.ts
@@ -24,12 +24,10 @@ export function resolveFlowCollection(
 ) {
   const isMap = fc.start.source === '{'
   const fcName = isMap ? 'flow map' : 'flow sequence'
-  let NodeClass = tag?.nodeClass
-  const MapClass = NodeClass || YAMLMap
-  const SeqClass = NodeClass || YAMLSeq
-  const coll = isMap
-    ? (new MapClass(ctx.schema) as YAMLMap.Parsed)
-    : (new SeqClass(ctx.schema) as YAMLSeq.Parsed)
+  let NodeClass = (tag?.nodeClass ?? (isMap ? YAMLMap : YAMLSeq)) as {
+    new (ctx: ComposeContext['schema']): YAMLMap.Parsed | YAMLSeq.Parsed
+  }
+  const coll = new NodeClass(ctx.schema)
   coll.flow = true
   const atRoot = ctx.atRoot
   if (atRoot) ctx.atRoot = false
diff --git a/src/schema/yaml-1.1/timestamp.ts b/src/schema/yaml-1.1/timestamp.ts
index 026c9efb..2093f3ae 100644
--- a/src/schema/yaml-1.1/timestamp.ts
+++ b/src/schema/yaml-1.1/timestamp.ts
@@ -47,7 +47,7 @@ function stringifySexagesimal(node: Scalar) {
   return (
     sign +
     parts
-      .map(n => String(n).padStart(2, '0')) //(n < 10 ? '0' + String(n) : String(n)))
+      .map(n => String(n).padStart(2, '0'))
       .join(':')
       .replace(/000000\d*$/, '') // % 60 may introduce error
   )