diff --git a/src/Umbraco.Core/IO/ShadowFileSystem.cs b/src/Umbraco.Core/IO/ShadowFileSystem.cs
index cb2f4e346c..8645399a0b 100644
--- a/src/Umbraco.Core/IO/ShadowFileSystem.cs
+++ b/src/Umbraco.Core/IO/ShadowFileSystem.cs
@@ -218,11 +218,11 @@ namespace Umbraco.Core.IO
             var normPath = NormPath(path);
             var shadows = Nodes.Where(kvp => IsChild(normPath, kvp.Key)).ToArray();
             var files = filter != null ? _fs.GetFiles(path, filter) : _fs.GetFiles(path);
-            var regexFilter = FilterToRegex(filter);
+            var wildcard = filter == null ? null : new WildcardExpression(filter);
             return files
                 .Except(shadows.Where(kvp => (kvp.Value.IsFile && kvp.Value.IsDelete) || kvp.Value.IsDir)
                     .Select(kvp => kvp.Key))
-                .Union(shadows.Where(kvp => kvp.Value.IsFile && kvp.Value.IsExist && FilterByRegex(kvp.Key, regexFilter)).Select(kvp => kvp.Key))
+                .Union(shadows.Where(kvp => kvp.Value.IsFile && kvp.Value.IsExist && (wildcard == null || wildcard.IsMatch(kvp.Key))).Select(kvp => kvp.Key))
                 .Distinct();
         }
 
@@ -326,32 +326,65 @@ namespace Umbraco.Core.IO
             _sfs.AddFile(path, physicalPath, overrideIfExists, copy);
             Nodes[normPath] = new ShadowNode(false, false);
         }
-        
-        /// <summary>
-        /// Helper function for filtering keys by Regex if a filter is specified.
-        /// </summary>
-        /// <param name="input"></param>
-        /// <param name="regexFilter"></param>
-        /// <returns></returns>
-        internal static bool FilterByRegex(string input, string regexFilter)
-        {
-            if (regexFilter == null) return true;
-            return regexFilter != string.Empty && Regex.IsMatch(input, regexFilter);
-        }
 
-        /// <summary>
-        /// Transforms a filter pattern into a Regex pattern
-        /// </summary>
-        /// <param name="pattern"></param>
-        /// <returns></returns>
-        /// <remarks>
-        /// Appending '$' only if not containing wildcard is stupid and broken.
-        /// It is however what seems to be what they're doing in .NET so we need to match the functionality.
-        /// </remarks>
-        internal static string FilterToRegex(string pattern)
+        // copied from System.Web.Util.Wildcard internal
+        internal class WildcardExpression
         {
-            if (pattern == null) return null;
-            return "^" + Regex.Escape(pattern).Replace("\\*", ".*").Replace("\\?", ".") + (pattern.Contains("*") ? string.Empty : "$");
+            private readonly string _pattern;
+            private readonly bool _caseInsensitive;
+            private Regex _regex;
+
+            private static Regex metaRegex = new Regex("[\\+\\{\\\\\\[\\|\\(\\)\\.\\^\\$]");
+            private static Regex questRegex = new Regex("\\?");
+            private static Regex starRegex = new Regex("\\*");
+            private static Regex commaRegex = new Regex(",");
+            private static Regex slashRegex = new Regex("(?=/)");
+            private static Regex backslashRegex = new Regex("(?=[\\\\:])");
+
+            public WildcardExpression(string pattern, bool caseInsensitive = true)
+            {
+                _pattern = pattern;
+                _caseInsensitive = caseInsensitive;
+            }
+
+            private void EnsureRegex(string pattern)
+            {
+                if (_regex != null) return;
+
+                var options = RegexOptions.None;
+
+                // match right-to-left (for speed) if the pattern starts with a *
+
+                if (pattern.Length > 0 && pattern[0] == '*')
+                    options = RegexOptions.RightToLeft | RegexOptions.Singleline;
+                else
+                    options = RegexOptions.Singleline;
+
+                // case insensitivity
+
+                if (_caseInsensitive)
+                    options |= RegexOptions.IgnoreCase | RegexOptions.CultureInvariant;
+
+                // Remove regex metacharacters
+
+                pattern = metaRegex.Replace(pattern, "\\$0");
+
+                // Replace wildcard metacharacters with regex codes
+
+                pattern = questRegex.Replace(pattern, ".");
+                pattern = starRegex.Replace(pattern, ".*");
+                pattern = commaRegex.Replace(pattern, "\\z|\\A");
+
+                // anchor the pattern at beginning and end, and return the regex
+
+                _regex = new Regex("\\A" + pattern + "\\z", options);
+            }
+
+            public bool IsMatch(string input)
+            {
+                EnsureRegex(_pattern);
+                return _regex.IsMatch(input);
+            }
         }
     }
 }
diff --git a/src/Umbraco.Tests/IO/ShadowFileSystemTests.cs b/src/Umbraco.Tests/IO/ShadowFileSystemTests.cs
index 03cc9364ce..80110698b5 100644
--- a/src/Umbraco.Tests/IO/ShadowFileSystemTests.cs
+++ b/src/Umbraco.Tests/IO/ShadowFileSystemTests.cs
@@ -805,101 +805,6 @@ namespace Umbraco.Tests.IO
             Assert.AreEqual(3, sfsFiles.Length);
         }
 
-        [Test]
-        [Ignore("Does not work on all environments, Directory.GetFiles is broken.")]
-        public void ShadowGetFilesUsingWildcardAndSingleCharacterFilter()
-        {
-            // Arrange
-            var path = IOHelper.MapPath("FileSysTests");
-            Directory.CreateDirectory(path);
-            Directory.CreateDirectory(path + "/ShadowTests");
-            Directory.CreateDirectory(path + "/ShadowSystem");
-
-            var fs = new PhysicalFileSystem(path + "/ShadowTests/", "ignore");
-            var sfs = new PhysicalFileSystem(path + "/ShadowSystem/", "ignore");
-            var ss = new ShadowFileSystem(fs, sfs);
-
-            // Act
-            File.WriteAllText(path + "/ShadowTests/f2.txt", "foo");
-            File.WriteAllText(path + "/ShadowTests/f2.doc", "foo");
-            File.WriteAllText(path + "/ShadowTests/f2.docx", "foo");
-            using (var ms = new MemoryStream(Encoding.UTF8.GetBytes("foo")))
-                ss.AddFile("f1.txt", ms);
-            using (var ms = new MemoryStream(Encoding.UTF8.GetBytes("foo")))
-                ss.AddFile("f1.doc", ms);
-            using (var ms = new MemoryStream(Encoding.UTF8.GetBytes("foo")))
-                ss.AddFile("f1.docx", ms);
-
-            // Assert
-            // ensure we get 6 files from the shadow
-            var getFiles = ss.GetFiles(string.Empty);
-            Assert.AreEqual(6, getFiles.Count());
-            var getFilesWithWildcardSinglecharFilter = ss.GetFiles(string.Empty, "*.d?c");
-
-            Assert.AreEqual(4, getFilesWithWildcardSinglecharFilter.Count());
-            var getFilesWithWildcardSinglecharFilter2 = ss.GetFiles(string.Empty, "*.d?cx");
-            Assert.AreEqual(2, getFilesWithWildcardSinglecharFilter2.Count());
-
-            var fsFiles = fs.GetFiles(string.Empty).ToArray();
-            Assert.AreEqual(3, fsFiles.Length);
-            var sfsFiles = sfs.GetFiles(string.Empty).ToArray();
-            Assert.AreEqual(3, sfsFiles.Length);
-        }
-
-        [Test]
-        [Ignore("Does not work on all environments, Directory.GetFiles is broken.")]
-        public void ShadowFileSystemFilterIsAsBrokenAsRealFileSystemFilter()
-        {
-            // Arrange
-            var path = IOHelper.MapPath("FileSysTests");
-            Directory.CreateDirectory(path);
-            Directory.CreateDirectory(path + "/filter");
-            // create files on disk and create a "fake" list of files to verify filters against
-            File.WriteAllText(path + "/filter/f1.txt", "foo");
-            File.WriteAllText(path + "/filter/f1.doc", "foo");
-            File.WriteAllText(path + "/filter/f1.docx", "foo");
-            var files = new string[]
-            {
-                "f1.txt",
-                "f1.doc",
-                "f1.docx",
-            };
-            var filter1 = "";
-            var filter2 = "*";
-            var filter3 = "*.doc";
-            var filter4 = "*.d?c";
-            var filter5 = "f1.doc";
-            var filter6 = "f1.d?c";
-            var filter7 = "**.d?c";
-            var filter8 = "f*.doc";
-
-            // Act & Assert
-            var result1Disk = Directory.GetFiles(path + "/filter/", filter1).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result1Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter1))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result1Disk, result1Fake);
-            var result2Disk = Directory.GetFiles(path + "/filter/", filter2).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result2Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter2))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result2Disk, result2Fake);
-            var result3Disk = Directory.GetFiles(path + "/filter/", filter3).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result3Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter3))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result3Disk, result3Fake);
-            var result4Disk = Directory.GetFiles(path + "/filter/", filter4).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result4Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter4))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result4Disk, result4Fake);
-            var result5Disk = Directory.GetFiles(path + "/filter/", filter5).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result5Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter5))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result5Disk, result5Fake);
-            var result6Disk = Directory.GetFiles(path + "/filter/", filter6).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result6Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter6))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result6Disk, result6Fake);
-            var result7Disk = Directory.GetFiles(path + "/filter/", filter7).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result7Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter7))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result7Disk, result7Fake);
-            var result8Disk = Directory.GetFiles(path + "/filter/", filter8).Select(Path.GetFileName).OrderBy(x => x).ToArray();
-            var result8Fake = files.Where(x => ShadowFileSystem.FilterByRegex(x, ShadowFileSystem.FilterToRegex(filter8))).OrderBy(x => x).ToArray();
-            Assert.AreEqual(result8Disk, result8Fake);
-        }
-
         /// <summary>
         /// Returns the full paths of the files on the disk.
         /// Note that this will be the *actual* path of the file, meaning a file existing on the initialized FS