diff --git a/xpfe/AppCores/src/nsBaseAppCore.h b/xpfe/AppCores/src/nsBaseAppCore.h
index 23eb2196617d..cd29248ebffa 100644
--- a/xpfe/AppCores/src/nsBaseAppCore.h
+++ b/xpfe/AppCores/src/nsBaseAppCore.h
@@ -27,7 +27,12 @@
 #include "nsIDOMBaseAppCore.h"
 #include "nsCOMPtr.h"
 
-class nsIDOMNode;
+// Cannot forward declare a class used with an nsCOMPtr.
+// see: http://www.mozilla.org/projects/xpcom/nsCOMPtr.html
+// class nsIDOMNode;
+
+#include "nsIDOMNode.h"
+
 class nsIDOMDocument;
 class nsIScriptContext;
 class nsIDOMWindow;
diff --git a/xpfe/AppCores/src/nsToolkitCore.h b/xpfe/AppCores/src/nsToolkitCore.h
index 3f490db4db27..609e23bb0d1d 100644
--- a/xpfe/AppCores/src/nsToolkitCore.h
+++ b/xpfe/AppCores/src/nsToolkitCore.h
@@ -28,9 +28,15 @@
 #include "nsIDOMToolkitCore.h"
 #include "nsBaseAppCore.h"
 
+
 class nsIDOMWindow;
 class nsIScriptContext;
-class nsIWebShellWindow;
+
+// Cannot forward declare a class used with an nsCOMPtr.
+// see: http://www.mozilla.org/projects/xpcom/nsCOMPtr.html
+//class nsIWebShellWindow;
+
+#include "nsIWebShellWindow.h"
 
 ////////////////////////////////////////////////////////////////////////////////
 // nsToolbarCore: