diff --git a/dlls/mshtml/mutation.c b/dlls/mshtml/mutation.c
index ba98d41db1e..19b4143a117 100644
--- a/dlls/mshtml/mutation.c
+++ b/dlls/mshtml/mutation.c
@@ -552,12 +552,12 @@ static void NSAPI nsDocumentObserver_EndLoad(nsIDocumentObserver *iface, nsIDocu
 }
 
 static void NSAPI nsDocumentObserver_ContentStatesChanged(nsIDocumentObserver *iface, nsIDocument *aDocument,
-        nsIContent *aContent, nsEventStates aStateMask)
+        nsIContent *aContent, nsEventStates *aStateMask)
 {
 }
 
 static void NSAPI nsDocumentObserver_DocumentStatesChanged(nsIDocumentObserver *iface, nsIDocument *aDocument,
-        nsEventStates aStateMask)
+        nsEventStates *aStateMask)
 {
 }
 
diff --git a/dlls/mshtml/nsiface.idl b/dlls/mshtml/nsiface.idl
index 7849ee5a64a..1477f2d6f85 100644
--- a/dlls/mshtml/nsiface.idl
+++ b/dlls/mshtml/nsiface.idl
@@ -3169,7 +3169,7 @@ interface nsIParser : nsISupports
 ]
 interface nsIDocumentObserver : nsIMutationObserver
 {
-    typedef int nsUpdateType;
+    typedef PRUint32 nsUpdateType;
 
     typedef struct {
         PRUint64 mStates;
@@ -3179,8 +3179,8 @@ interface nsIDocumentObserver : nsIMutationObserver
     void EndUpdate(nsIDocument *aDocument, nsUpdateType aUpdateType);
     void BeginLoad(nsIDocument *aDocument);
     void EndLoad(nsIDocument *aDocument);
-    void ContentStatesChanged(nsIDocument *aDocument, nsIContent *aContent, nsEventStates aStateMask);
-    void DocumentStatesChanged(nsIDocument *aDocument, nsEventStates aStateMask);
+    void ContentStatesChanged(nsIDocument *aDocument, nsIContent *aContent, nsEventStates *aStateMask);
+    void DocumentStatesChanged(nsIDocument *aDocument, nsEventStates *aStateMask);
     void StyleSheetAdded(nsIDocument *aDocument, nsIStyleSheet *aStyleSheet, PRBool aDocumentSheet);
     void StyleSheetRemoved(nsIDocument *aDocument, nsIStyleSheet *aStyleSheet, PRBool aDocumentSheet);
     void StyleSheetApplicableStateChanged(nsIDocument *aDocument, nsIStyleSheet *aStyleSheet,