diff --git a/thys/Implicational_Logic/ROOT b/thys/Implicational_Logic/ROOT
--- a/thys/Implicational_Logic/ROOT
+++ b/thys/Implicational_Logic/ROOT
@@ -1,8 +1,9 @@
 chapter AFP
 
 session Implicational_Logic (AFP) = HOL +
   options [timeout = 3600]
   theories
     Implicational_Logic
+    Implicational_Logic_Appendix
   document_files
     "root.tex"