diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6eecc53..7ad1556 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [3.6.0] - 2023-11-25
+## [3.6.2] - 2023-11-26
+### Changed
+- Fix EnqueueDequeue
+
+## [3.6.1] - 2023-11-25
 ### Changed
 - Fix doc of FloorSum
 
diff --git a/Directory.Build.props b/Directory.Build.props
index 311c35e..55d954a 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -7,8 +7,8 @@
     <RepositoryUrl>https://github.com/kzrnm/ac-library-csharp</RepositoryUrl>
     <PackageReleaseNotes>https://github.com/kzrnm/ac-library-csharp/blob/main/CHANGELOG.md</PackageReleaseNotes>
 
-    <Version>3.6.1</Version>
-    <AssemblyVersion>3.6.1.101</AssemblyVersion>
+    <Version>3.6.2</Version>
+    <AssemblyVersion>3.6.2.101</AssemblyVersion>
     <RepositoryCommit Condition="'$(GIT_COMMIT)' != ''">$(GIT_COMMIT)</RepositoryCommit>
 
     <SignAssembly>True</SignAssembly>
diff --git a/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp.cs b/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp.cs
index bfbe24a..953b425 100644
--- a/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp.cs
+++ b/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp.cs
@@ -69,7 +69,7 @@ public T Dequeue()
         public T EnqueueDequeue(T value)
         {
             var res = data[0];
-            if (_comparer.Compare(value, res) <= 0)
+            if (Count == 0 || _comparer.Compare(value, res) <= 0)
             {
                 return value;
             }
diff --git a/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp`2.cs b/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp`2.cs
index 12bf2c9..8153f5b 100644
--- a/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp`2.cs
+++ b/Source/ac-library-csharp/STL/PriorityQueue/PriorityQueueOp`2.cs
@@ -91,7 +91,7 @@ public KeyValuePair<TKey, TValue> Dequeue()
         public KeyValuePair<TKey, TValue> EnqueueDequeue(TKey key, TValue value)
         {
             var res = KeyValuePair.Create(keys[0], values[0]);
-            if (_comparer.Compare(key, keys[0]) <= 0)
+            if (Count == 0 || _comparer.Compare(key, keys[0]) <= 0)
             {
                 return KeyValuePair.Create(key, value);
             }
diff --git a/Test/ac-library-csharp.Test/STL/PriorityQueueTest.cs b/Test/ac-library-csharp.Test/STL/PriorityQueueTest.cs
index 026741c..98ca2a5 100644
--- a/Test/ac-library-csharp.Test/STL/PriorityQueueTest.cs
+++ b/Test/ac-library-csharp.Test/STL/PriorityQueueTest.cs
@@ -216,6 +216,9 @@ public void EnqueueDequeue()
         {
             var pq1 = new PriorityQueue<int>();
             var pq2 = new PriorityQueue<int>();
+
+            pq1.EnqueueDequeue(1).Should().Be(1);
+
             for (int i = 10; i > 0; i--)
             {
                 pq1.Enqueue(i);
@@ -242,6 +245,9 @@ public void EnqueueDequeueKV()
         {
             var pq1 = new PriorityQueueDictionary<int, string>();
             var pq2 = new PriorityQueueDictionary<int, string>();
+
+            pq1.EnqueueDequeue(1, "ab").Should().Be(KeyValuePair.Create(1, "ab"));
+
             for (int i = 10; i > 0; i--)
             {
                 pq1.Enqueue(i, i.ToString());