diff --git a/bin/mm-server b/bin/mm-server
index 04b48d6d..10f34bc4 100755
--- a/bin/mm-server
+++ b/bin/mm-server
@@ -15,7 +15,7 @@ trap("TSTP") do
       puts "== Build complete"
     end
   end
-end
+end if Signal.list.has_key? "TSTP"
 
 require 'optparse'