diff --git a/parser/htmlparser/public/nsIParserNode.h b/parser/htmlparser/public/nsIParserNode.h
index 78f46c0d7a8d..2b0d127abb58 100644
--- a/parser/htmlparser/public/nsIParserNode.h
+++ b/parser/htmlparser/public/nsIParserNode.h
@@ -167,7 +167,7 @@ class nsIParserNode { // XXX Should be nsAParserNode
      * @update	rickg 06June2000
      * @return  void
      */
-    virtual void GetSource(nsString& aString)=0;
+    virtual void GetSource(nsString& aString) const = 0;
 
     /** Release all the objects you're holding
      * @update	harishd 08/02/00
diff --git a/parser/htmlparser/src/nsParserNode.cpp b/parser/htmlparser/src/nsParserNode.cpp
index 882302ec8ec5..a59bba07907f 100644
--- a/parser/htmlparser/src/nsParserNode.cpp
+++ b/parser/htmlparser/src/nsParserNode.cpp
@@ -269,7 +269,7 @@ nsCParserNode::PopAttributeToken() {
  * @return  void
  */
 void 
-nsCParserNode::GetSource(nsString& aString) 
+nsCParserNode::GetSource(nsString& aString) const
 {
   eHTMLTags theTag = mToken ? (eHTMLTags)mToken->GetTypeID() : eHTMLTag_unknown;
   aString.Assign(PRUnichar('<'));
@@ -353,7 +353,7 @@ nsCParserStartNode::PopAttributeToken()
   return NS_STATIC_CAST(CToken*, mAttributes.Pop());
 }
 
-void nsCParserStartNode::GetSource(nsString& aString) 
+void nsCParserStartNode::GetSource(nsString& aString) const
 {
   aString.Assign(PRUnichar('<'));
   const PRUnichar* theTagName = 
diff --git a/parser/htmlparser/src/nsParserNode.h b/parser/htmlparser/src/nsParserNode.h
index a525dafeec07..36d6145296ee 100644
--- a/parser/htmlparser/src/nsParserNode.h
+++ b/parser/htmlparser/src/nsParserNode.h
@@ -243,7 +243,7 @@ class nsCParserNode :  public nsIParserNode {
      * @update	rickg 06June2000
      * @return  void
      */
-    virtual void GetSource(nsString& aString);
+    virtual void GetSource(nsString& aString) const;
 
     /**
      * This pair of methods allows us to set a generic bit (for arbitrary use)
@@ -314,7 +314,7 @@ public:
     virtual const    nsAString& GetKeyAt(PRUint32 anIndex) const;
     virtual const    nsAString& GetValueAt(PRUint32 anIndex) const;
     virtual CToken*  PopAttributeToken();
-    virtual void     GetSource(nsString& aString);
+    virtual void     GetSource(nsString& aString) const;
     virtual nsresult ReleaseAll();
 protected:
     nsDeque  mAttributes;