diff --git a/widget/src/beos/nsToolkit.cpp b/widget/src/beos/nsToolkit.cpp
index c0fa888cffe..9abd876a9e2 100644
--- a/widget/src/beos/nsToolkit.cpp
+++ b/widget/src/beos/nsToolkit.cpp
@@ -276,7 +276,16 @@ void nsToolkit::CallMethodAsync(MethodInfo *info)
 
 	id.data = info;
 	id.sync = false;
-	write_port_etc(eventport, WM_CALLMETHOD, &id, sizeof(id), B_TIMEOUT, 0);
+	
+	// Check message count to not exceed the port's capacity.
+	// There seems to be a BeOS bug that allows more 
+	// messages on a port than its capacity.
+	port_info portinfo;
+	if (get_port_info(eventport, &portinfo) != B_OK)
+	  return;
+
+	if (port_count(eventport) < portinfo.capacity - 20) 
+	  write_port_etc(eventport, WM_CALLMETHOD, &id, sizeof(id), B_TIMEOUT, 0);
 }
 
 //------------------------------------------------------------------------- 
diff --git a/xpcom/threads/plevent.c b/xpcom/threads/plevent.c
index 366fb727309..2406472c51f 100644
--- a/xpcom/threads/plevent.c
+++ b/xpcom/threads/plevent.c
@@ -767,7 +767,7 @@ failed:
 	{
 		/* create port
 		 */
-		self->eventport = create_port(100, portname);
+		self->eventport = create_port(500, portname);
 
 		/* We don't use the sem, but it has to be there
 		 */