diff --git a/widget/src/cocoa/nsChildView.mm b/widget/src/cocoa/nsChildView.mm
index 896789d5a20..656ac79ffad 100644
--- a/widget/src/cocoa/nsChildView.mm
+++ b/widget/src/cocoa/nsChildView.mm
@@ -1819,6 +1819,7 @@ NSEvent* globalDragEvent = nil;
   [self registerForDraggedTypes:[NSArray arrayWithObjects:NSFilenamesPboardType,
                                                           NSStringPboardType,
                                                           NSURLPboardType,
+                                                          kWildcardPboardType,
                                                           nil]];
 
   return self;
diff --git a/widget/src/cocoa/nsDragService.h b/widget/src/cocoa/nsDragService.h
index e7f290b26b8..9abceda3e36 100644
--- a/widget/src/cocoa/nsDragService.h
+++ b/widget/src/cocoa/nsDragService.h
@@ -43,6 +43,8 @@
 
 #include <Cocoa/Cocoa.h>
 
+extern NSString* const kWildcardPboardType;
+
 class nsILocalFile;
 class nsIDOMDragEvent;
 
diff --git a/widget/src/cocoa/nsDragService.mm b/widget/src/cocoa/nsDragService.mm
index d7e3c7e0303..7bb4d885572 100644
--- a/widget/src/cocoa/nsDragService.mm
+++ b/widget/src/cocoa/nsDragService.mm
@@ -69,6 +69,8 @@ extern NSPasteboard* globalDragPboard;
 extern NSView* globalDragView;
 extern NSEvent* globalDragEvent;
 
+NSString* const kWildcardPboardType = @"MozillaWildcard";
+
 NS_IMPL_ADDREF_INHERITED(nsDragService, nsBaseDragService)
 NS_IMPL_RELEASE_INHERITED(nsDragService, nsBaseDragService)
 NS_IMPL_QUERY_INTERFACE2(nsDragService, nsIDragService, nsIDragSession)
@@ -224,8 +226,17 @@ static nsresult SetUpDragClipboard(nsISupportsArray* aTransferableArray)
       id currentValue = [pasteboardOutputDict valueForKey:currentKey];
       if (currentKey == NSStringPboardType)
         [generalPBoard setString:currentValue forType:currentKey];
-      else
+      else {
         [generalPBoard setData:currentValue forType:currentKey];
+        // Record miscellaneous types of data a second time, under a
+        // generic type that is always registered with Cocoa as
+        // draggable. This allows types dynamically synthesized from
+        // JS to work; if in the future several different types of
+        // drag data need to be distinguished, it will be the
+        // responsibility of higher-level drag code to detect the
+        // situation (which it would normally have to do anyway.)
+        [generalPBoard setData:nil forType:kWildcardPboardType];
+      }
     }
   }