1 files changed, 1 insertions, 1 deletions
diff --git a/isa/isa.el b/isa/isa.el
index 84aacf60..34e92c38 100644
--- a/isa/isa.el
+++ b/isa/isa.el
@@ -346,7 +346,7 @@ isa-proofscript-mode."
 	 (string-match ".thy" (buffer-file-name)))
     (thy-mode)
     ;; Hack for splash screen
-    (if (and proof-mode-hook
+    (if (and (boundp 'proof-mode-hook)
 	     (memq 'proof-splash-timeout-waiter proof-mode-hook))
 	(proof-splash-timeout-waiter))
     ;; Has this theory file already been loaded by Isabelle?