diff --git a/thys/VerifyThis2019/ROOT b/thys/VerifyThis2019/ROOT
--- a/thys/VerifyThis2019/ROOT
+++ b/thys/VerifyThis2019/ROOT
@@ -1,15 +1,17 @@
 chapter AFP
 
 session VerifyThis2019 (AFP) = Sepref_IICF +
- options [timeout = 600]
- theories [document = false]
+  options [timeout = 600]
+  directories
+    "lib"
+  theories [document = false]
     "lib/VTcomp"
   theories
     Challenge1A
     Challenge1B
     Challenge2A
     Challenge2B
     Parallel_Multiset_Fold
     Challenge3
   document_files
-    "root.tex"
\ No newline at end of file
+    "root.tex"