diff --git a/releasenotes.txt b/releasenotes.txt
index bb2a7bd..922bac6 100644
--- a/releasenotes.txt
+++ b/releasenotes.txt
@@ -1,5 +1,19 @@
 -- Release Notes --
 
+Release 0.7.1.2, 21 March 2012
+
+* The Modify action now supports replacing a header based on a regex in the value field.
+  Any string in the value for a Modify action which matches the form /foo/bar/ triggers the code.
+  foo can be a regular expression and bar is the string which replaces the match.
+  Example: 
+    Action: Modify
+    Name: Host
+    Value: {^w{0,3}\.?domain.com$}{192.168.254.65}
+    This will change www.domain.com and domain.com to 192.168.254.65 if found in the Host header.
+	(Updated 28th)
+
+--
+
 Release 0.7.1.1, 30 November 2011
 
 * Fixed bug 24593: Addon toolbar is displayed every time a new window is opened
diff --git a/src/components/modifyheaders-service.js b/src/components/modifyheaders-service.js
index e82f503..6c87fb8 100644
--- a/src/components/modifyheaders-service.js
+++ b/src/components/modifyheaders-service.js
@@ -273,8 +273,20 @@ if (!ModifyHeaders.Proxy) {
 							// This is the default for action = Modify
 							var headerValue = headers[i].value;
 							var headerAppend = false;
-							
-							if (headers[i].action == "Add") {
+
+							// Could add a new action "Regex" instead.
+							// For the following code to run, the value supplied by the user
+							// should be of the form:  {foo}{bar}
+							// where 'foo' can be a regular expression
+							// and 'bar' is the string to replace the match with.
+							if(headers[i].action == "Modify") {
+								var isRegex = headerValue.match(/^\{(.*?)\}\{(.*?)\}$/);
+								if(isRegex.length>0) { // OR == 2 to be stricter
+									var currentHeaderValue = subject.getRequestHeader(headerName);
+									// 0 = {foo}{bar}; 1 = foo; 2 = bar;
+									headerValue = currentHeaderValue.replace(new RegExp(isRegex[1]), isRegex[2]);
+								}
+							} else if (headers[i].action == "Add") {
 								headerAppend = true;
 							} else if (headers[i].action == "Filter") {
 								headerValue = "";