diff --git a/storage/innobase/trx/trx0trx.cc b/storage/innobase/trx/trx0trx.cc
index 0a0a02b1a50..8272bb67e49 100644
--- a/storage/innobase/trx/trx0trx.cc
+++ b/storage/innobase/trx/trx0trx.cc
@@ -1406,15 +1406,12 @@ which case still the trx->no is assigned.
 @param[in,out]  trx   the modified transaction
 @return true if added to the serialisation_list (non read-only trx) */
 static inline bool trx_add_to_serialisation_list(trx_t *trx) {
-  trx_sys_serialisation_mutex_enter();
-
   trx->no = trx_sys_allocate_trx_no();
 
   /* Update the latest transaction number. */
   ut_d(trx_sys->rw_max_trx_no = trx->no);
 
   if (trx->read_only) {
-    trx_sys_serialisation_mutex_exit();
     return false;
   }
 
@@ -1424,7 +1421,6 @@ static inline bool trx_add_to_serialisation_list(trx_t *trx) {
     trx_sys->serialisation_min_trx_no.store(trx->no);
   }
 
-  trx_sys_serialisation_mutex_exit();
   return true;
 }
 
@@ -1486,10 +1482,12 @@ static bool trx_serialisation_number_get(
       elem.insert(temp_rseg);
     }
 
-    mutex_enter(&purge_sys->pq_mutex);
-
+    trx_sys_serialisation_mutex_enter();
     added_trx_no = trx_add_to_serialisation_list(trx);
 
+    mutex_enter(&purge_sys->pq_mutex);
+    trx_sys_serialisation_mutex_exit();
+
     elem.set_trx_no(trx->no);
 
     purge_sys->purge_queue->push(std::move(elem));
@@ -1497,7 +1495,9 @@ static bool trx_serialisation_number_get(
     mutex_exit(&purge_sys->pq_mutex);
 
   } else {
+    trx_sys_serialisation_mutex_enter();
     added_trx_no = trx_add_to_serialisation_list(trx);
+    trx_sys_serialisation_mutex_exit();
   }
 
   return (added_trx_no);