diff --git a/Aspects/RegularExpression.cs b/Aspects/RegularExpression.cs
index e8504f6..05aeff2 100644
--- a/Aspects/RegularExpression.cs
+++ b/Aspects/RegularExpression.cs
@@ -574,18 +574,31 @@ public static class RegularExpression
 
         #region Guid
         /// <summary>
-        /// Regular expression pattern which matches ...
+        /// Regular expression pattern which matches GUID.
         /// </summary>
         public const string RexGuid = @"(?i:^(?:[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})|(?:[0-9a-f]{32})$)";
 
         readonly static Lazy<Regex> _rexGuid = new Lazy<Regex>(() => new Regex(RexGuid, RegexOptions.Compiled));
 
         /// <summary>
-        /// Gets a Regex object which matches ...
+        /// Gets a Regex object which matches GUID
         /// </summary>
         public static Regex Guid => _rexGuid.Value;
         #endregion
 
+        #region Content-type or Accepts header values:
+        /// <summary>
+        /// Regular expression pattern which matches the value of the HTTP headers Accept and content-type, incl. vendor specific MIME types.
+        /// </summary>
+        public const string RexContentType = @"(?i:)^(?<type>text|application)/(?:(?<vendor>[^\s,;+-]+)(?:-(?<version>[^\s,;+]+))?\+)?(?<format>[^\s\+,;]+)$";
+
+        readonly static Lazy<Regex> _contentType = new Lazy<Regex>(() => new Regex(RexContentType, RegexOptions.Compiled));
+
+        /// <summary>
+        /// Regular expression pattern which matches the value of the HTTP headers Accept and content-type, incl. vendor specific MIME types.
+        /// </summary>
+        public static Regex ContentType => _contentType.Value;
+        #endregion
 
         #region ByteArray
         /// <summary>
diff --git a/Aspects/Wcf/Bindings/WebContentTypeMapperDefaultJson.cs b/Aspects/Wcf/Bindings/WebContentTypeMapperDefaultJson.cs
index c08695d..f00df57 100644
--- a/Aspects/Wcf/Bindings/WebContentTypeMapperDefaultJson.cs
+++ b/Aspects/Wcf/Bindings/WebContentTypeMapperDefaultJson.cs
@@ -1,5 +1,4 @@
-using System;
-using System.ServiceModel.Channels;
+using System.ServiceModel.Channels;
 
 namespace vm.Aspects.Wcf.Bindings
 {
@@ -19,12 +18,20 @@ public override WebContentFormat GetMessageFormatForContentType(
             if (string.IsNullOrWhiteSpace(contentType))
                 return WebContentFormat.Default;
 
-            if (contentType.StartsWith("text/javascript", StringComparison.OrdinalIgnoreCase)  ||
-                contentType.StartsWith("text/plain", StringComparison.OrdinalIgnoreCase))
-                return WebContentFormat.Json;
+            var match = RegularExpression.ContentType.Match(contentType);
 
-            if (contentType.StartsWith("text/xml", StringComparison.OrdinalIgnoreCase))
-                return WebContentFormat.Xml;
+            if (match.Success)
+                switch (match.Groups["format"].Value.ToUpperInvariant())
+                {
+                case "JAVASCRIPT":
+                case "JSON":
+                case "X-JAVASCRIPT":
+                case "X-JSON":
+                    return WebContentFormat.Json;
+
+                case "XML":
+                    return WebContentFormat.Xml;
+                }
 
             return WebContentFormat.Default;
         }