--- a/src/gnat/gnat_config.ml	2017-10-18 09:07:03.118919785 +0200
+++ b/src/gnat/gnat_config.ml	2017-10-18 09:07:45.198216939 +0200
@@ -12,10 +12,7 @@
   | Limit_Check of Gnat_expl.check
   | Limit_Line of Gnat_loc.loc
 
-let spark_prefix =
-  (Filename.dirname
-          (Filename.dirname (Filename.dirname
-          (Filename.dirname Sys.executable_name))))
+let spark_prefix = "/usr"
 
 let rec file_concat l =
   match l with