diff --git a/scripts/sync.sh b/scripts/sync.sh
index 8210a950..6751a51c 100755
--- a/scripts/sync.sh
+++ b/scripts/sync.sh
@@ -24,6 +24,11 @@ book_example() {
   local src=book/src/applet/prelude/$1.rs
   local dst=examples/rust/$2/src/lib.rs
   if [ $dst -nt $src ]; then
+    # START DEBUGGING
+    set -x
+    stat -c%Y $src
+    stat -c%Y $dst
+    # END DEBUGGING
     t "Update $src instead of $dst"
     e "$dst seems to have been manually modified"
   fi