diff --git a/timer.lua b/timer.lua
index 823433e..6ea3f7b 100644
--- a/timer.lua
+++ b/timer.lua
@@ -88,7 +88,9 @@ function Timer:every(delay, after, count)
 end
 
 function Timer:cancel(handle)
-    self.functions[handle] = nil
+    if handle then
+        self.functions[handle] = nil
+    end
 end
 
 function Timer:clear()