diff -r 6e9df530b441 -r 57a76e4728ed src/HOL/Mirabelle/ex/Ex.thy
--- a/src/HOL/Mirabelle/ex/Ex.thy	Sun Sep 23 19:59:53 2018 +0200
+++ b/src/HOL/Mirabelle/ex/Ex.thy	Sun Sep 23 20:33:35 2018 +0200
@@ -3,7 +3,7 @@
 
 ML \<open>
   val rc = Isabelle_System.bash
-    "cd \"$ISABELLE_HOME/src/HOL/Analysis\"; isabelle mirabelle arith Inner_Product.thy";
+    "cd \"$ISABELLE_HOME/src/HOL/Analysis\"; if isabelle build -n \"$MIRABELLE_LOGIC\"; then isabelle mirabelle arith Inner_Product.thy; fi";
   if rc <> 0 then error ("Mirabelle example failed: " ^ string_of_int rc)
   else ();
 \<close> \<comment> \<open>some arbitrary small test case\<close>