diff --git a/sql/binlog.cc b/sql/binlog.cc
index e7ad65d82e1..e9403430948 100644
--- a/sql/binlog.cc
+++ b/sql/binlog.cc
@@ -6133,8 +6133,7 @@ err:
   shall be acquired, false if the called is already the owner of the lock_index.
   @param need_update_threads If we want to update the log coordinates of
                              all threads. False for relay logs, true otherwise.
-  @param decrease_log_space  If not null, decrement this variable of
-                             the amount of log space freed
+  @param decrease_log_space  If not null, return the amount of log space freed
   @param auto_purge          True if this is an automatic purge.

   @note
@@ -6461,7 +6460,7 @@ int MYSQL_BIN_LOG::purge_index_entry(THD *thd, ulonglong *decrease_log_space,
             DBUG_SET("-d,wait_in_purge_index_entry");
           };);

-          if (decrease_log_space) *decrease_log_space -= s.st_size;
+          if (decrease_log_space) *decrease_log_space += s.st_size;
         } else {
           if (my_errno() == ENOENT) {
             if (thd) {
diff --git a/sql/rpl_applier_reader.cc b/sql/rpl_applier_reader.cc
index 18de4c84eea..a79515dc940 100644
--- a/sql/rpl_applier_reader.cc
+++ b/sql/rpl_applier_reader.cc
@@ -533,14 +533,16 @@ bool Rpl_applier_reader::purge_applied_logs() {

   DBUG_EXECUTE_IF("crash_before_purge_logs", DBUG_SUICIDE(););

-  mysql_mutex_lock(&m_rli->log_space_lock);
+  ulonglong log_space_purged = 0;

   if (m_rli->relay_log.purge_logs(
           m_rli->get_group_relay_log_name(), false /* include */,
           false /*need_lock_index*/, false /*need_update_threads*/,
-          &m_rli->log_space_total, true) != 0)
+          &log_space_purged, true) != 0)
     m_errmsg = "Error purging processed logs";

+  mysql_mutex_lock(&m_rli->log_space_lock);
+  m_rli->log_space_total -= log_space_purged;
   // Tell the I/O thread to take the relay_log_space_limit into account
   m_rli->ignore_log_space_limit = false;
   mysql_cond_broadcast(&m_rli->log_space_cond);