diff --git a/tests/Core/TestTwitterUtils.cs b/tests/Core/TestTwitterUtils.cs
new file mode 100644
index 00000000..a1e8f62c
--- /dev/null
+++ b/tests/Core/TestTwitterUtils.cs
@@ -0,0 +1,39 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using TweetDuck.Core.Utils;
+
+namespace UnitTests.Core{
+    [TestClass]
+    public class TestTwitterUtils{
+        [TestMethod]
+        public void TestAccountRegex(){
+            Assert.IsTrue(TwitterUtils.RegexAccount.IsMatch("http://twitter.com/chylexmc"));
+            Assert.IsTrue(TwitterUtils.RegexAccount.IsMatch("https://twitter.com/chylexmc"));
+            Assert.IsTrue(TwitterUtils.RegexAccount.IsMatch("http://twitter.com/chylexmc/"));
+            Assert.IsTrue(TwitterUtils.RegexAccount.IsMatch("https://twitter.com/chylexmc/"));
+
+            Assert.AreEqual("chylexmc", TwitterUtils.RegexAccount.Match("http://twitter.com/chylexmc").Groups[1].Value);
+            Assert.AreEqual("123", TwitterUtils.RegexAccount.Match("http://twitter.com/123").Groups[1].Value);
+            Assert.AreEqual("_", TwitterUtils.RegexAccount.Match("http://twitter.com/_").Groups[1].Value);
+
+            Assert.AreEqual("Abc_123", TwitterUtils.RegexAccount.Match("http://twitter.com/Abc_123").Groups[1].Value);
+            Assert.AreEqual("Abc_123", TwitterUtils.RegexAccount.Match("https://twitter.com/Abc_123/").Groups[1].Value);
+
+            Assert.IsFalse(TwitterUtils.RegexAccount.IsMatch("http://twitter.com/"));
+            Assert.IsFalse(TwitterUtils.RegexAccount.IsMatch("http://twitter.com/chylexmc/status"));
+            Assert.IsFalse(TwitterUtils.RegexAccount.IsMatch("http://nottwitter.com/chylexmc"));
+            Assert.IsFalse(TwitterUtils.RegexAccount.IsMatch("www.twitter.com/chylexmc"));
+        }
+
+        [TestMethod]
+        public void TestImageQualityLink(){
+            Assert.AreEqual("https://pbs.twimg.com/profile_images/123.jpg", TwitterUtils.GetImageLink("https://pbs.twimg.com/profile_images/123.jpg", TwitterUtils.ImageQuality.Default));
+            Assert.AreEqual("https://pbs.twimg.com/profile_images/123.jpg", TwitterUtils.GetImageLink("https://pbs.twimg.com/profile_images/123.jpg", TwitterUtils.ImageQuality.Orig));
+
+            Assert.AreEqual("https://pbs.twimg.com/media/123.jpg:small", TwitterUtils.GetImageLink("https://pbs.twimg.com/media/123.jpg:small", TwitterUtils.ImageQuality.Default));
+            Assert.AreEqual("https://pbs.twimg.com/media/123.jpg:orig", TwitterUtils.GetImageLink("https://pbs.twimg.com/media/123.jpg:small", TwitterUtils.ImageQuality.Orig));
+
+            Assert.AreEqual("https://pbs.twimg.com/media/123.jpg:large", TwitterUtils.GetImageLink("https://pbs.twimg.com/media/123.jpg:large", TwitterUtils.ImageQuality.Default));
+            Assert.AreEqual("https://pbs.twimg.com/media/123.jpg:orig", TwitterUtils.GetImageLink("https://pbs.twimg.com/media/123.jpg:large", TwitterUtils.ImageQuality.Orig));
+        }
+    }
+}
diff --git a/tests/Data/TestCombinedFileStream.cs b/tests/Data/TestCombinedFileStream.cs
index e49f5365..6e6a839e 100644
--- a/tests/Data/TestCombinedFileStream.cs
+++ b/tests/Data/TestCombinedFileStream.cs
@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Linq;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using TweetDuck.Data;
 
@@ -139,5 +140,31 @@ public void TestEntryWriteWithDirectory(){
 
             Directory.Delete("cfs_directory", true);
         }
+
+        [TestMethod]
+        public void TestLongIdentifierSuccess(){
+            TestUtils.WriteText("cfs_long_identifier_fail_in", "test");
+
+            string identifier = string.Join("", Enumerable.Repeat("x", 255));
+
+            using(CombinedFileStream cfs = new CombinedFileStream(TestUtils.WriteFile("cfs_long_identifier_success"))){
+                cfs.WriteFile(identifier, "cfs_long_identifier_fail_in");
+                cfs.Flush();
+            }
+
+            using(CombinedFileStream cfs = new CombinedFileStream(TestUtils.ReadFile("cfs_long_identifier_success"))){
+                Assert.AreEqual(identifier, cfs.ReadFile().Identifier);
+            }
+        }
+
+        [TestMethod]
+        [ExpectedException(typeof(ArgumentOutOfRangeException))]
+        public void TestLongIdentifierFail(){
+            TestUtils.WriteText("cfs_long_identifier_fail_in", "test");
+
+            using(CombinedFileStream cfs = new CombinedFileStream(TestUtils.WriteFile("cfs_long_identifier_fail"))){
+                cfs.WriteFile(string.Join("", Enumerable.Repeat("x", 256)), "cfs_long_identifier_fail_in");
+            }
+        }
     }
 }
diff --git a/tests/UnitTests.csproj b/tests/UnitTests.csproj
index b4aa6eee..036a1ae8 100644
--- a/tests/UnitTests.csproj
+++ b/tests/UnitTests.csproj
@@ -48,6 +48,7 @@
   </Choose>
   <ItemGroup>
     <Compile Include="Core\TestStringUtils.cs" />
+    <Compile Include="Core\TestTwitterUtils.cs" />
     <Compile Include="Data\TestCombinedFileStream.cs" />
     <Compile Include="Core\TestBrowserUtils.cs" />
     <Compile Include="Data\TestCommandLineArgs.cs" />