diff --git a/client/mysqltest.cc b/client/mysqltest.cc
index 0f0ecb37c41..6e7dfacd897 100644
--- a/client/mysqltest.cc
+++ b/client/mysqltest.cc
@@ -5350,7 +5350,8 @@ void do_sync_with_master2(struct st_command *command, long offset,
     /* master_pos_wait returned NULL or < 0 */
     fprintf(stderr, "analyze: sync_with_master\n");
 
-    sprintf(query_buf2, "show slave \"%s\" status", connection_name);
+    snprintf(query_buf2, sizeof(query_buf2), "show slave \"%s\" status",
+             connection_name);
 
     if (!mysql_query(mysql, query_buf2))
     {
diff --git a/sql/slave.cc b/sql/slave.cc
index 9b844f0f371..89fd29f9ade 100644
--- a/sql/slave.cc
+++ b/sql/slave.cc
@@ -2725,7 +2725,8 @@ after_set_capability:
             "The slave I/O thread stops because a fatal out-of-memory error "
             "is encountered when it tries to set "
             "@slave_gtid_until_before_gtids.";
-        sprintf(err_buff, "%s Error: Out of memory", errmsg);
+        snprintf(err_buff, sizeof(err_buff), "%s Error: Out of memory",
+                 errmsg);
         goto err;
       }
 
@@ -2745,7 +2746,8 @@ after_set_capability:
           /* Fatal error */
           errmsg= "The slave I/O thread stops because a fatal error is "
             "encountered when it tries to set @slave_gtid_until_before_gtids.";
-          sprintf(err_buff, "%s Error: %s", errmsg, mysql_error(mysql));
+          snprintf(err_buff, sizeof(err_buff), "%s Error: %s", errmsg,
+                   mysql_error(mysql));
           goto err;
         }
       }