diff --git a/src/Umbraco.Core/StringExtensions.cs b/src/Umbraco.Core/StringExtensions.cs
index a3236be982..13804a4ac8 100644
--- a/src/Umbraco.Core/StringExtensions.cs
+++ b/src/Umbraco.Core/StringExtensions.cs
@@ -870,5 +870,34 @@ namespace Umbraco.Core
             
             return alias;
         }
+        
+        /// <summary>
+        /// An extension method that returns a new string in which all occurrences of a 
+        /// specified string in the current instance are replaced with another specified string.
+        /// StringComparison specifies the type of search to use for the specified string.
+        /// </summary>
+        /// <param name="source">Current instance of the string</param>
+        /// <param name="oldString">Specified string to replace</param>
+        /// <param name="newString">Specified string to inject</param>
+        /// <param name="stringComparison">String Comparison object to specify search type</param>
+        /// <returns>Updated string</returns>
+        public static string Replace(this string source, string oldString, string newString, StringComparison stringComparison)
+        {
+            var index = source.IndexOf(oldString, stringComparison);
+
+            // Determine if we found a match
+            var matchFound = index >= 0;
+
+            if (matchFound)
+            {
+                // Remove the old text
+                source = source.Remove(index, oldString.Length);
+
+                // Add the replacemenet text
+                source = source.Insert(index, newString);
+            }
+
+            return source;
+        }
     }
 }
diff --git a/src/Umbraco.Web/umbraco.presentation/umbraco/uQuery/MediaExtensions.cs b/src/Umbraco.Web/umbraco.presentation/umbraco/uQuery/MediaExtensions.cs
index 74d7103396..322a11d74d 100644
--- a/src/Umbraco.Web/umbraco.presentation/umbraco/uQuery/MediaExtensions.cs
+++ b/src/Umbraco.Web/umbraco.presentation/umbraco/uQuery/MediaExtensions.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Xml;
 using umbraco.cms.businesslogic.media;
+using Umbraco.Core;
 
 namespace umbraco
 {
@@ -215,7 +216,7 @@ namespace umbraco
 				if (!string.IsNullOrEmpty(url))
 				{
 					var extension = media.GetProperty<string>("umbracoExtension");
-					return url.Replace(string.Concat(".", extension), "_thumb.jpg");
+                    return url.Replace(string.Concat(".", extension), "_thumb.jpg", StringComparison.InvariantCultureIgnoreCase);
 				}
 			}