diff --git a/src/environments/groupthm/groupthm.dtx b/src/environments/groupthm/groupthm.dtx
index 783875b..14b8f09 100644
--- a/src/environments/groupthm/groupthm.dtx
+++ b/src/environments/groupthm/groupthm.dtx
@@ -2709,6 +2709,13 @@
 \hook_gput_code:nnn { enddocument / afterlastpage } { groupthm }
   {
     \let \declaretheorem \@@_fake_declare_theorem:w
+    \iow_now:cx { @auxout }
+      {
+        \token_to_str:N \ExplSyntaxOn
+        \int_set:Nn \g_@@_cache_version_aux_int
+          { \int_use:N \g_@@_cache_version_document_int }
+        \token_to_str:N \ExplSyntaxOff
+      }
   }
 %    \end{macrocode}
 %