diff --git a/mozilla/docshell/base/nsWebShell.cpp b/mozilla/docshell/base/nsWebShell.cpp
index 8cf8f4f01af..e2f89b8ec89 100644
--- a/mozilla/docshell/base/nsWebShell.cpp
+++ b/mozilla/docshell/base/nsWebShell.cpp
@@ -1226,7 +1226,7 @@ nsWebShell::OnEndURLLoad(nsIDocumentLoader* loader,
 #endif
 
 nsresult
-nsWebShell :: GetControllerForCommand ( nsAReadableString & inCommand, nsIController** outController )
+nsWebShell :: GetControllerForCommand ( const nsAReadableString & inCommand, nsIController** outController )
 {
   nsresult rv = NS_ERROR_FAILURE;
   
@@ -1244,7 +1244,7 @@ nsWebShell :: GetControllerForCommand ( nsAReadableString & inCommand, nsIContro
 
 
 nsresult
-nsWebShell :: IsCommandEnabled ( nsAReadableString & inCommand, PRBool* outEnabled )
+nsWebShell :: IsCommandEnabled ( const nsAReadableString & inCommand, PRBool* outEnabled )
 {
   nsresult rv = NS_ERROR_FAILURE;
   
@@ -1258,7 +1258,7 @@ nsWebShell :: IsCommandEnabled ( nsAReadableString & inCommand, PRBool* outEnabl
 
 
 nsresult
-nsWebShell :: DoCommand ( nsAReadableString & inCommand )
+nsWebShell :: DoCommand ( const nsAReadableString & inCommand )
 {
   nsresult rv = NS_ERROR_FAILURE;
   
diff --git a/mozilla/docshell/base/nsWebShell.h b/mozilla/docshell/base/nsWebShell.h
index 403495a40a2..cdcc28b50a0 100644
--- a/mozilla/docshell/base/nsWebShell.h
+++ b/mozilla/docshell/base/nsWebShell.h
@@ -126,9 +126,9 @@ protected:
   void InitFrameData();
   
     // helpers for executing commands
-  virtual nsresult GetControllerForCommand ( nsAReadableString & inCommand, nsIController** outController ) ;
-  virtual nsresult IsCommandEnabled ( nsAReadableString & inCommand, PRBool* outEnabled ) ;
-  virtual nsresult DoCommand ( nsAReadableString & inCommand ) ;
+  virtual nsresult GetControllerForCommand ( const nsAReadableString & inCommand, nsIController** outController ) ;
+  virtual nsresult IsCommandEnabled ( const nsAReadableString & inCommand, PRBool* outEnabled ) ;
+  virtual nsresult DoCommand ( const nsAReadableString & inCommand ) ;
 
   nsIEventQueue* mThreadEventQueue;