diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index a802d536a9b..ef23b652a82 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -5465,7 +5465,7 @@ nsContentUtils::SetDataTransferInEvent(WidgetDragEvent* aDragEvent)
   // created before the event fires, so it should already be set. For other
   // drag events, get the object from the drag session.
   NS_ASSERTION(aDragEvent->mMessage != NS_DRAGDROP_GESTURE &&
-               aDragEvent->mMessage != NS_DRAGDROP_START,
+               aDragEvent->mMessage != eDragStart,
                "draggesture event created without a dataTransfer");
 
   nsCOMPtr<nsIDragSession> dragSession = GetDragSession();
diff --git a/dom/events/DataTransfer.cpp b/dom/events/DataTransfer.cpp
index bb15bec0243..b28548643c6 100644
--- a/dom/events/DataTransfer.cpp
+++ b/dom/events/DataTransfer.cpp
@@ -88,7 +88,7 @@ DataTransfer::DataTransfer(nsISupports* aParent, EventMessage aEventMessage,
   // external usage, cache the data from the native clipboard or drag.
   if (aEventMessage == NS_CUT ||
       aEventMessage == NS_COPY ||
-      aEventMessage == NS_DRAGDROP_START ||
+      aEventMessage == eDragStart ||
       aEventMessage == NS_DRAGDROP_GESTURE) {
     mReadOnly = false;
   } else if (mIsExternal) {
@@ -135,7 +135,7 @@ DataTransfer::DataTransfer(nsISupports* aParent,
   // modifiable, but those events should have been using the first constructor
   // above.
   NS_ASSERTION(aEventMessage != NS_DRAGDROP_GESTURE &&
-               aEventMessage != NS_DRAGDROP_START,
+               aEventMessage != eDragStart,
                "invalid event type for DataTransfer constructor");
 }
 
diff --git a/dom/events/EventNameList.h b/dom/events/EventNameList.h
index 26810f772aa..76c25f632f3 100644
--- a/dom/events/EventNameList.h
+++ b/dom/events/EventNameList.h
@@ -199,7 +199,7 @@ EVENT(dragover,
       EventNameType_HTMLXUL,
       eDragEventClass)
 EVENT(dragstart,
-      NS_DRAGDROP_START,
+      eDragStart,
       EventNameType_HTMLXUL,
       eDragEventClass)
 EVENT(drop,
diff --git a/dom/events/EventStateManager.cpp b/dom/events/EventStateManager.cpp
index 930cc3addb3..4f49bd706fa 100644
--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -1637,7 +1637,7 @@ EventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
         return;
 
       nsRefPtr<DataTransfer> dataTransfer =
-        new DataTransfer(window, NS_DRAGDROP_START, false, -1);
+        new DataTransfer(window, eDragStart, false, -1);
 
       nsCOMPtr<nsISelection> selection;
       nsCOMPtr<nsIContent> eventContent, targetContent;
@@ -1663,7 +1663,7 @@ EventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
 
       // get the widget from the target frame
       WidgetDragEvent startEvent(aEvent->mFlags.mIsTrusted,
-                                 NS_DRAGDROP_START, widget);
+                                 eDragStart, widget);
       FillInEventFromGestureDown(&startEvent);
 
       WidgetDragEvent gestureEvent(aEvent->mFlags.mIsTrusted,
diff --git a/dom/ipc/ContentChild.cpp b/dom/ipc/ContentChild.cpp
index 964e7c14f82..c8c0fb79f39 100644
--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -2809,7 +2809,7 @@ ContentChild::RecvInvokeDragSession(nsTArray<IPCDataTransfer>&& aTransfers,
     if (session) {
       session->SetDragAction(aAction);
       nsCOMPtr<DataTransfer> dataTransfer =
-        new DataTransfer(nullptr, NS_DRAGDROP_START, false, -1);
+        new DataTransfer(nullptr, eDragStart, false, -1);
       for (uint32_t i = 0; i < aTransfers.Length(); ++i) {
         auto& items = aTransfers[i].items();
         for (uint32_t j = 0; j < items.Length(); ++j) {
diff --git a/dom/xul/nsXULElement.cpp b/dom/xul/nsXULElement.cpp
index 7ae3278012f..af447f87bac 100644
--- a/dom/xul/nsXULElement.cpp
+++ b/dom/xul/nsXULElement.cpp
@@ -1269,7 +1269,7 @@ nsXULElement::PreHandleEvent(EventChainPreVisitor& aVisitor)
          aVisitor.mEvent->mMessage == eMouseDoubleClick ||
          aVisitor.mEvent->mMessage == NS_XUL_COMMAND ||
          aVisitor.mEvent->mMessage == eContextMenu ||
-         aVisitor.mEvent->mMessage == NS_DRAGDROP_START ||
+         aVisitor.mEvent->mMessage == eDragStart ||
          aVisitor.mEvent->mMessage == NS_DRAGDROP_GESTURE)) {
         // Don't propagate these events from native anonymous scrollbar.
         aVisitor.mCanHandle = true;
diff --git a/widget/EventMessageList.h b/widget/EventMessageList.h
index 75afb9124e5..e89e7542b91 100644
--- a/widget/EventMessageList.h
+++ b/widget/EventMessageList.h
@@ -109,7 +109,7 @@ NS_EVENT_MESSAGE(NS_DRAGDROP_DRAGDROP,  eDragDropEventFirst + 3)
 NS_EVENT_MESSAGE(NS_DRAGDROP_GESTURE,   eDragDropEventFirst + 4)
 NS_EVENT_MESSAGE(NS_DRAGDROP_DRAG,      eDragDropEventFirst + 5)
 NS_EVENT_MESSAGE(NS_DRAGDROP_END,       eDragDropEventFirst + 6)
-NS_EVENT_MESSAGE(NS_DRAGDROP_START,     eDragDropEventFirst + 7)
+NS_EVENT_MESSAGE(eDragStart,            eDragDropEventFirst + 7)
 NS_EVENT_MESSAGE(eDrop,                 eDragDropEventFirst + 8)
 NS_EVENT_MESSAGE(eDragLeave,            eDragDropEventFirst + 9)
 NS_EVENT_MESSAGE(eDragDropEventLast,    eDragLeave)
diff --git a/widget/WidgetEventImpl.cpp b/widget/WidgetEventImpl.cpp
index 947f34218ea..148b91d2c95 100644
--- a/widget/WidgetEventImpl.cpp
+++ b/widget/WidgetEventImpl.cpp
@@ -106,7 +106,7 @@ WidgetEvent::HasDragEventMessage() const
     case NS_DRAGDROP_GESTURE:
     case NS_DRAGDROP_DRAG:
     case NS_DRAGDROP_END:
-    case NS_DRAGDROP_START:
+    case eDragStart:
     case eDrop:
     case eDragLeave:
       return true;