diff --git a/toolkit/components/satchel/src/nsStorageFormHistory.cpp b/toolkit/components/satchel/src/nsStorageFormHistory.cpp
index a75574966dab..86c38af6977c 100644
--- a/toolkit/components/satchel/src/nsStorageFormHistory.cpp
+++ b/toolkit/components/satchel/src/nsStorageFormHistory.cpp
@@ -133,13 +133,7 @@ nsFormHistoryResult::RemoveValueAt(PRInt32 aRowIndex, PRBool aRemoveFromDB)
 
 NS_INTERFACE_MAP_BEGIN(nsFormHistory)
   NS_INTERFACE_MAP_ENTRY(nsIFormHistory)
-  // Have to do this one by hand because it's an ambiguous conversion
-  // to nsISupports.
-  if (aIID.Equals(NS_GET_IID(nsFormHistory))) {
-    NS_ADDREF_THIS();
-    *aInstancePtr = this;
-    return NS_OK;
-  } else
+  NS_INTERFACE_MAP_ENTRY(nsIFormHistoryPrivate)
   NS_INTERFACE_MAP_ENTRY(nsIObserver)
   NS_INTERFACE_MAP_ENTRY(nsIFormSubmitObserver)
   NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
@@ -604,10 +598,10 @@ nsFormHistoryImporter::ImportFormHistory(nsIFile *aFile,
   reader.EnumerateColumns(EnumerateColumnsCB, &data);
 
   // Add the rows to form history
-  nsCOMPtr<nsFormHistory> formHistory = do_QueryInterface(aFormHistory);
-  NS_ENSURE_TRUE(formHistory, NS_ERROR_FAILURE);
+  nsCOMPtr<nsIFormHistoryPrivate> fhPrivate = do_QueryInterface(aFormHistory);
+  NS_ENSURE_TRUE(fhPrivate, NS_ERROR_FAILURE);
 
-  mozIStorageConnection *conn = formHistory->GetStorageConnection();
+  mozIStorageConnection *conn = fhPrivate->GetStorageConnection();
   NS_ENSURE_TRUE(conn, NS_ERROR_NOT_INITIALIZED);
   mozStorageTransaction transaction(conn, PR_FALSE);
 
diff --git a/toolkit/components/satchel/src/nsStorageFormHistory.h b/toolkit/components/satchel/src/nsStorageFormHistory.h
index 1154f38164cc..690a8ab40a90 100644
--- a/toolkit/components/satchel/src/nsStorageFormHistory.h
+++ b/toolkit/components/satchel/src/nsStorageFormHistory.h
@@ -59,22 +59,33 @@
 
 class nsIAutoCompleteSimpleResult;
 class nsIAutoCompleteResult;
+class nsFormHistory;
 
-#define NS_FORMHISTORY_IID \
+#define NS_IFORMHISTORYPRIVATE_IID \
 {0xc4a47315, 0xaeb5, 0x4039, {0x9f, 0x34, 0x45, 0x11, 0xb3, 0xa7, 0x58, 0xdd}}
 
+class nsIFormHistoryPrivate : public nsISupports
+{
+ public:
+#ifdef MOZILLA_1_8_BRANCH
+  NS_DEFINE_STATIC_IID_ACCESSOR(NS_IFORMHISTORYPRIVATE_IID)
+#else
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IFORMHISTORYPRIVATE_IID)
+#endif
+
+  mozIStorageConnection* GetStorageConnection() { return mDBConn; }
+
+ protected:
+  nsCOMPtr<mozIStorageConnection> mDBConn;
+};
+
 class nsFormHistory : public nsIFormHistory,
+                      public nsIFormHistoryPrivate,
                       public nsIObserver,
                       public nsIFormSubmitObserver,
                       public nsSupportsWeakReference
 {
 public:
-#ifdef MOZILLA_1_8_BRANCH
-  NS_DEFINE_STATIC_IID_ACCESSOR(NS_FORMHISTORY_IID)
-#else
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_FORMHISTORY_IID)
-#endif
-
   NS_DECL_ISUPPORTS
   NS_DECL_NSIFORMHISTORY
   NS_DECL_NSIOBSERVER
@@ -93,8 +104,6 @@ public:
       return gFormHistory;
     }
 
-  mozIStorageConnection* GetStorageConnection() { return mDBConn; }
-
   nsresult AutoCompleteSearch(const nsAString &aInputName,
 			      const nsAString &aInputValue,
                               nsIAutoCompleteSimpleResult *aPrevResult,
@@ -115,7 +124,6 @@ public:
 
   nsCOMPtr<nsIPrefBranch> mPrefBranch;
   nsCOMPtr<mozIStorageService> mStorageService;
-  nsCOMPtr<mozIStorageConnection> mDBConn;
   nsCOMPtr<mozIStorageStatement> mDBGetMatchingField;
   nsCOMPtr<mozIStorageStatement> mDBFindEntry;
   nsCOMPtr<mozIStorageStatement> mDBFindEntryByName;