diff --git a/asyncdispatch2/timer.nim b/asyncdispatch2/timer.nim
index 6daf4ea..a0c2c01 100644
--- a/asyncdispatch2/timer.nim
+++ b/asyncdispatch2/timer.nim
@@ -30,7 +30,7 @@ elif defined(macosx):
   proc fastEpochTime*(): uint64 {.inline.} =
     var t: Timeval
     posix_gettimeofday(t)
-    result = (t.tv_sec * 1_000 + t.tv_usec div 1_000)
+    result = (uint64(t.tv_sec) * 1_000 + uint64(t.tv_usec) div 1_000)
 
 elif defined(posix):