diff --git a/thys/FOL_Axiomatic/ROOT b/thys/FOL_Axiomatic/ROOT
--- a/thys/FOL_Axiomatic/ROOT
+++ b/thys/FOL_Axiomatic/ROOT
@@ -1,9 +1,11 @@
 chapter AFP
 
 session FOL_Axiomatic (AFP) = "HOL" +
   options [timeout = 300]
+  sessions
+    "HOL-Library"
   theories
     FOL_Axiomatic
   document_files
     "root.tex"
     "root.bib"