diff --git a/QRCoder/PayloadGenerator.cs b/QRCoder/PayloadGenerator.cs
index 48336a73..031b4cc8 100644
--- a/QRCoder/PayloadGenerator.cs
+++ b/QRCoder/PayloadGenerator.cs
@@ -311,7 +311,7 @@ public class Url : Payload
             private readonly string url;
 
             /// <summary>
-            /// Generates a link. If not given, http/https protocol will be added.
+            /// Generates a link. If the protocol is not specified, the http protocol will be added.
             /// </summary>
             /// <param name="url">Link url target</param>
             public Url(string url)
@@ -321,7 +321,7 @@ public Url(string url)
 
             public override string ToString()
             {
-                return (!this.url.StartsWith("http") ? "http://" + this.url : this.url);
+                return (!this.url.StartsWith("http", StringComparison.OrdinalIgnoreCase) ? "http://" + this.url : this.url);
             }
         }
 
diff --git a/QRCoderTests/PayloadGeneratorTests.cs b/QRCoderTests/PayloadGeneratorTests.cs
index 2e90e3ce..1500f124 100644
--- a/QRCoderTests/PayloadGeneratorTests.cs
+++ b/QRCoderTests/PayloadGeneratorTests.cs
@@ -744,6 +744,18 @@ public void url_should_build_https()
         }
 
 
+        [Fact]
+        [Category("PayloadGenerator/Url")]
+        public void url_should_build_https_all_caps()
+        {
+            var url = "HTTPS://CODE-BUDE.NET";
+
+            var generator = new PayloadGenerator.Url(url);
+
+            generator.ToString().ShouldBe("HTTPS://CODE-BUDE.NET");
+        }
+
+
         [Fact]
         [Category("PayloadGenerator/Url")]
         public void url_should_add_http()