diff --git a/BuildMonitor.Test/BranchUrlTests.cs b/BuildMonitor.Test/BranchUrlTests.cs
new file mode 100644
index 0000000..c7a0918
--- /dev/null
+++ b/BuildMonitor.Test/BranchUrlTests.cs
@@ -0,0 +1,47 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.BuildMonitor.Test;
+
+using ktsu.Semantics.Strings;
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+/// <summary>
+/// Covers "Open Branch URL" and "Copy Branch URL". The branch name went into the URL unescaped, so a
+/// <c>#</c> started a fragment and a <c>%</c> read as a percent-escape, and the link pointed at the
+/// wrong branch or a 404 (ktsu-dev/BuildMonitor#386).
+/// </summary>
+[TestClass]
+public sealed class BranchUrlTests
+{
+	private sealed class StubProvider : BuildProvider
+	{
+		internal override BuildProviderName Name { get; } = "Stub".As<BuildProviderName>();
+
+		internal override Task UpdateRepositoriesAsync(Owner owner) => Task.CompletedTask;
+		internal override Task UpdateBuildsAsync(Repository repository) => Task.CompletedTask;
+		internal override Task UpdateBuildAsync(Build build) => Task.CompletedTask;
+		internal override Task UpdateRunAsync(Run run) => Task.CompletedTask;
+	}
+
+	private static Build CreateBuild()
+	{
+		Owner owner = new StubProvider().CreateOwner("o".As<OwnerName>());
+		Repository repository = owner.CreateRepository("r".As<RepositoryName>());
+		return repository.CreateBuild("build".As<BuildName>());
+	}
+
+	[TestMethod]
+	[DataRow("feature/foo", "https://github.com/o/r/tree/feature/foo")]
+	[DataRow("main", "https://github.com/o/r/tree/main")]
+	[DataRow("fix/#123-crash", "https://github.com/o/r/tree/fix/%23123-crash")]
+	[DataRow("feature/50%", "https://github.com/o/r/tree/feature/50%25")]
+	public void BranchUrlEscapesEachSegmentAndKeepsSeparators(string branch, string expected)
+	{
+		// Act
+		string url = BuildMonitor.GetBranchUrl(CreateBuild(), branch.As<BranchName>());
+
+		// Assert
+		Assert.AreEqual(expected, url);
+	}
+}
diff --git a/BuildMonitor/BuildMonitor.cs b/BuildMonitor/BuildMonitor.cs
index 1f2e783..8ce14bc 100644
--- a/BuildMonitor/BuildMonitor.cs
+++ b/BuildMonitor/BuildMonitor.cs
@@ -1338,7 +1338,12 @@ private static void CopyRunUrl(Run run)
 
 	private static string GetWorkflowUrl(Build build) => $"https://github.com/{build.Owner.Name}/{build.Repository.Name}/actions/workflows/{build.Id}";
 
-	private static string GetBranchUrl(Build build, BranchName branch) => $"https://github.com/{build.Owner.Name}/{build.Repository.Name}/tree/{branch}";
+	/// <summary>
+	/// Escapes each segment of the branch name and keeps its <c>/</c> separators, so a <c>#</c> or
+	/// <c>%</c> in the name stays part of the path rather than starting a fragment or an escape.
+	/// </summary>
+	internal static string GetBranchUrl(Build build, BranchName branch) =>
+		$"https://github.com/{build.Owner.Name}/{build.Repository.Name}/tree/{string.Join('/', branch.ToString().Split('/').Select(Uri.EscapeDataString))}";
 
 	private static string GetRunUrl(Run run) => $"https://github.com/{run.Owner.Name}/{run.Repository.Name}/actions/runs/{run.Id}";