diff --git a/content/base/src/nsXMLHttpRequest.cpp b/content/base/src/nsXMLHttpRequest.cpp
index d539f43637c4..8e5db40498a5 100644
--- a/content/base/src/nsXMLHttpRequest.cpp
+++ b/content/base/src/nsXMLHttpRequest.cpp
@@ -2491,6 +2491,16 @@ nsXMLHttpRequest::Send(nsIVariant *aBody)
                                               &haveCharset, &charsetStart,
                                               &charsetEnd);
         if (NS_SUCCEEDED(rv)) {
+          // special case: the extracted charset is quoted with single quotes
+          // -- for the purpose of preserving what was set we want to handle
+          // them as delimiters (although they aren't really)
+          if (specifiedCharset.Length() >= 2 &&
+              specifiedCharset.First() == '\'' &&
+              specifiedCharset.Last() == '\'') {
+            specifiedCharset = Substring(specifiedCharset, 1,
+                                         specifiedCharset.Length() - 2);
+          }
+
           // If the content-type the page set already has a charset parameter,
           // and it's the same charset, up to case, as |charset|, just send the
           // page-set content-type header.  Apparently at least
diff --git a/netwerk/base/src/nsURLHelper.cpp b/netwerk/base/src/nsURLHelper.cpp
index 22022220e662..61e7fbb92219 100644
--- a/netwerk/base/src/nsURLHelper.cpp
+++ b/netwerk/base/src/nsURLHelper.cpp
@@ -808,7 +808,7 @@ net_FindMediaDelimiter(const nsCString& flatStr,
     do {
         // searchStart points to the spot from which we should start looking
         // for the delimiter.
-        const char delimStr[] = { delimiter, '"', '\'', '\0' };
+        const char delimStr[] = { delimiter, '"', '\0' };
         PRUint32 curDelimPos = flatStr.FindCharInSet(delimStr, searchStart);
         if (curDelimPos == PRUint32(kNotFound))
             return flatStr.Length();
@@ -893,7 +893,7 @@ net_ParseMediaType(const nsACString &aMediaTypeStr,
         // '(' in the trailing trim set to catch media-type comments, which are
         // not at all standard, but may occur in rare cases.
         charset = net_FindCharNotInSet(charset, charsetEnd, HTTP_LWS);
-        if (*charset == '"' || *charset == '\'') {
+        if (*charset == '"') {
             charsetEnd =
                 start + net_FindStringEnd(flatStr, charset - start, *charset);
             charset++;
diff --git a/netwerk/test/unit/test_extract_charset_from_content_type.js b/netwerk/test/unit/test_extract_charset_from_content_type.js
index 46497f070cd2..47d9d2289f25 100644
--- a/netwerk/test/unit/test_extract_charset_from_content_type.js
+++ b/netwerk/test/unit/test_extract_charset_from_content_type.js
@@ -121,15 +121,15 @@ function run_test() {
   hadCharset =
     netutil.extractCharsetFromContentType("text/html; charset='ISO-8859-1'",
 					  charset, charsetStart, charsetEnd);
-  check(true, "ISO-8859-1", 9, 31);
+  check(true, "'ISO-8859-1'", 9, 31);
 
   hadCharset =
-    netutil.extractCharsetFromContentType("text/html; charset='ISO-8859-1', text/html",
+    netutil.extractCharsetFromContentType("text/html; charset=\"ISO-8859-1\", text/html",
 					  charset, charsetStart, charsetEnd);
   check(true, "ISO-8859-1", 9, 31);
 
   hadCharset =
-    netutil.extractCharsetFromContentType("text/html; charset='ISO-8859-1', text/html; charset=UTF8",
+    netutil.extractCharsetFromContentType("text/html; charset=\"ISO-8859-1\", text/html; charset=UTF8",
 					  charset, charsetStart, charsetEnd);
   check(true, "UTF8", 42, 56);
 
@@ -144,17 +144,17 @@ function run_test() {
   check(false, "", 41, 41);
 
   hadCharset =
-    netutil.extractCharsetFromContentType("text/plain, TEXT/HTML; charset='ISO-8859-1', text/html, TEXT/HTML",
+    netutil.extractCharsetFromContentType("text/plain, TEXT/HTML; charset=\"ISO-8859-1\", text/html, TEXT/HTML",
 					  charset, charsetStart, charsetEnd);
   check(true, "ISO-8859-1", 21, 43);
 
   hadCharset =
-    netutil.extractCharsetFromContentType('text/plain, TEXT/HTML; param="charset=UTF8"; charset=\'ISO-8859-1\'; param2="charset=UTF16", text/html, TEXT/HTML',
+    netutil.extractCharsetFromContentType('text/plain, TEXT/HTML; param="charset=UTF8"; charset="ISO-8859-1"; param2="charset=UTF16", text/html, TEXT/HTML',
 					  charset, charsetStart, charsetEnd);
   check(true, "ISO-8859-1", 43, 65);
 
   hadCharset =
-    netutil.extractCharsetFromContentType('text/plain, TEXT/HTML; param=charset=UTF8; charset=\'ISO-8859-1\'; param2=charset=UTF16, text/html, TEXT/HTML',
+    netutil.extractCharsetFromContentType('text/plain, TEXT/HTML; param=charset=UTF8; charset="ISO-8859-1"; param2=charset=UTF16, text/html, TEXT/HTML',
 					  charset, charsetStart, charsetEnd);
   check(true, "ISO-8859-1", 41, 63);
 
diff --git a/netwerk/test/unit/test_parse_content_type.js b/netwerk/test/unit/test_parse_content_type.js
index 327a5d486fc2..3ee2c243a9b7 100644
--- a/netwerk/test/unit/test_parse_content_type.js
+++ b/netwerk/test/unit/test_parse_content_type.js
@@ -56,6 +56,7 @@ function check(aType, aCharset, aHadCharset) {
 function run_test() {
   var netutil = Components.classes["@mozilla.org/network/util;1"]
                           .getService(Components.interfaces.nsINetUtil);
+
   type = netutil.parseContentType("text/html", charset, hadCharset);
   check("text/html", "", false);
 
@@ -88,13 +89,13 @@ function run_test() {
 
   type = netutil.parseContentType("text/html; charset='ISO-8859-1'",
 				  charset, hadCharset);
-  check("text/html", "ISO-8859-1", true);
+  check("text/html", "'ISO-8859-1'", true);
 
-  type = netutil.parseContentType("text/html; charset='ISO-8859-1', text/html",
+  type = netutil.parseContentType("text/html; charset=\"ISO-8859-1\", text/html",
 				  charset, hadCharset);
   check("text/html", "ISO-8859-1", true);
 
-  type = netutil.parseContentType("text/html; charset='ISO-8859-1', text/html; charset=UTF8",
+  type = netutil.parseContentType("text/html; charset=\"ISO-8859-1\", text/html; charset=UTF8",
 				  charset, hadCharset);
   check("text/html", "UTF8", true);
 
@@ -104,13 +105,13 @@ function run_test() {
   type = netutil.parseContentType("text/html; charset=ISO-8859-1, TEXT/plain", charset, hadCharset);
   check("text/plain", "", true);
 
-  type = netutil.parseContentType("text/plain, TEXT/HTML; charset='ISO-8859-1', text/html, TEXT/HTML", charset, hadCharset);
+  type = netutil.parseContentType("text/plain, TEXT/HTML; charset=ISO-8859-1, text/html, TEXT/HTML", charset, hadCharset);
   check("text/html", "ISO-8859-1", true);
 
-  type = netutil.parseContentType('text/plain, TEXT/HTML; param="charset=UTF8"; charset=\'ISO-8859-1\'; param2="charset=UTF16", text/html, TEXT/HTML', charset, hadCharset);
+  type = netutil.parseContentType('text/plain, TEXT/HTML; param="charset=UTF8"; charset="ISO-8859-1"; param2="charset=UTF16", text/html, TEXT/HTML', charset, hadCharset);
   check("text/html", "ISO-8859-1", true);
 
-  type = netutil.parseContentType('text/plain, TEXT/HTML; param=charset=UTF8; charset=\'ISO-8859-1\'; param2=charset=UTF16, text/html, TEXT/HTML', charset, hadCharset);
+  type = netutil.parseContentType('text/plain, TEXT/HTML; param=charset=UTF8; charset="ISO-8859-1"; param2=charset=UTF16, text/html, TEXT/HTML', charset, hadCharset);
   check("text/html", "ISO-8859-1", true);  
 
   type = netutil.parseContentType("text/plain; param= , text/html", charset, hadCharset);
@@ -134,4 +135,13 @@ function run_test() {
   type = netutil.parseContentType('text/plain, TEXT/HTML; param="charset=UTF8"; ; param2="charset=UTF16", text/html, TEXT/HTML', charset, hadCharset);
   check("text/html", "", false);
 
+  // Bug 700589
+
+  // check that single quote doesn't confuse parsing of subsequent parameters
+  type = netutil.parseContentType("text/plain; x='; charset=\"UTF-8\"", charset, hadCharset);
+  check("text/plain", "UTF-8", true);
+
+  // check that single quotes do not get removed from extracted charset
+  type = netutil.parseContentType("text/plain; charset='UTF-8'", charset, hadCharset);
+  check("text/plain", "'UTF-8'", true);
 }