diff --git a/PreMailer.Net/PreMailer.Net.Tests/ImportRuleCssSourceTests.cs b/PreMailer.Net/PreMailer.Net.Tests/ImportRuleCssSourceTests.cs
index 0b9d185..a441b40 100644
--- a/PreMailer.Net/PreMailer.Net.Tests/ImportRuleCssSourceTests.cs
+++ b/PreMailer.Net/PreMailer.Net.Tests/ImportRuleCssSourceTests.cs
@@ -203,6 +203,24 @@ public void ItShould_HandleCircularImports_WithoutInfiniteLoop()
 			_webDownloader.Verify(w => w.DownloadString(It.Is<Uri>(u => u.ToString() == "https://a.com/circular2.css")), Times.Once);
 		}
 
+		[Fact]
+		public void ItShould_PreservePortNumber_WhenResolvingRelativeImports()
+		{
+			var baseUri = new Uri("https://localhost:8080/styles/main.css");
+			var css = "@import \"variables.css\";";
+			var variablesCss = "body { color: red; }";
+
+			_webDownloader
+				.Setup(w => w.DownloadString(It.Is<Uri>(u => u.ToString() == "https://localhost:8080/styles/variables.css")))
+				.Returns(variablesCss);
+
+			var sut = new ImportRuleCssSource();
+
+			var result = sut.GetCss(baseUri, css).ToList();
+
+			_webDownloader.Verify(w => w.DownloadString(It.Is<Uri>(u => u.ToString() == "https://localhost:8080/styles/variables.css")), Times.Once);
+		}
+
 		private string CreateCss(IEnumerable<string> imports)
 		{
 			var builder = new StringBuilder();
diff --git a/PreMailer.Net/PreMailer.Net/Sources/ImportRuleCssSource.cs b/PreMailer.Net/PreMailer.Net/Sources/ImportRuleCssSource.cs
index 0217f61..3cd1ef0 100644
--- a/PreMailer.Net/PreMailer.Net/Sources/ImportRuleCssSource.cs
+++ b/PreMailer.Net/PreMailer.Net/Sources/ImportRuleCssSource.cs
@@ -83,7 +83,6 @@ private static Uri GetBaseUri(Uri downloadUri)
 		{
 			var baseUrl = new UriBuilder(downloadUri)
 			{
-				Port = -1 /* Excludes the port number */,
 				Query = string.Empty
 			};