diff --git a/htmlparser/src/nsIParser.h b/htmlparser/src/nsIParser.h
index 2e81dab008cd..9dfba85e56eb 100644
--- a/htmlparser/src/nsIParser.h
+++ b/htmlparser/src/nsIParser.h
@@ -350,6 +350,8 @@ const PRUnichar kNullCh           = '\0';
 
 #define kHTMLTextContentType  "text/html"
 #define kXMLTextContentType   "text/xml"
+#define kXMLApplicationContentType "application/xml"
+#define kXHTMLApplicationContentType "application/xhtml+xml"
 #define kXULTextContentType   "application/vnd.mozilla.xul+xml"
 #define kRDFTextContentType   "text/rdf"
 #define kXIFTextContentType   "text/xif"
diff --git a/parser/htmlparser/src/nsIParser.h b/parser/htmlparser/src/nsIParser.h
index 2e81dab008cd..9dfba85e56eb 100644
--- a/parser/htmlparser/src/nsIParser.h
+++ b/parser/htmlparser/src/nsIParser.h
@@ -350,6 +350,8 @@ const PRUnichar kNullCh           = '\0';
 
 #define kHTMLTextContentType  "text/html"
 #define kXMLTextContentType   "text/xml"
+#define kXMLApplicationContentType "application/xml"
+#define kXHTMLApplicationContentType "application/xhtml+xml"
 #define kXULTextContentType   "application/vnd.mozilla.xul+xml"
 #define kRDFTextContentType   "text/rdf"
 #define kXIFTextContentType   "text/xif"