1 files changed, 3 insertions, 0 deletions
diff --git a/lib/rbot/timer.rb b/lib/rbot/timer.rb
index c87c9c4d..db0c6ea1 100644
--- a/lib/rbot/timer.rb
+++ b/lib/rbot/timer.rb
@@ -117,16 +117,19 @@ module Timer
 
     # block action with handle +handle+
     def block(handle)
+      raise "no such timer #{handle}" unless @timers[handle]
       @timers[handle].blocked = true
     end
 
     # unblock action with handle +handle+
     def unblock(handle)
+      raise "no such timer #{handle}" unless @timers[handle]
       @timers[handle].blocked = false
     end
 
     # reschedule action with handle +handle+ to change its period
     def reschedule(handle, period)
+      raise "no such timer #{handle}" unless @timers[handle]
       @timers[handle].reschedule(period)
     end