diff --git a/lib/spring/application_manager.rb b/lib/spring/application_manager.rb
index <HASH>..<HASH> 100644
--- a/lib/spring/application_manager.rb
+++ b/lib/spring/application_manager.rb
@@ -59,7 +59,7 @@ module Spring
     end
 
     def stop
-      Process.kill('TERM', pid)
+      Process.kill('TERM', pid) if pid
     end
 
     private
Don't try to kill if pid is nil