diff --git a/django/db/backends/mysql/operations.py b/django/db/backends/mysql/operations.py
index 973a5548ff..07b5e85ba0 100644
--- a/django/db/backends/mysql/operations.py
+++ b/django/db/backends/mysql/operations.py
@@ -1,4 +1,3 @@
-import decimal
 import uuid
 
 from django.conf import settings
@@ -262,12 +261,6 @@ class DatabaseOperations(BaseDatabaseOperations):
     def binary_placeholder_sql(self, value):
         return '_binary %s' if value is not None and not hasattr(value, 'as_sql') else '%s'
 
-    def convert_durationfield_value(self, value, expression, connection):
-        # DurationFields can return a Decimal in MariaDB.
-        if isinstance(value, decimal.Decimal):
-            value = float(value)
-        return super().convert_durationfield_value(value, expression, connection)
-
     def subtract_temporals(self, internal_type, lhs, rhs):
         lhs_sql, lhs_params = lhs
         rhs_sql, rhs_params = rhs
@@ -275,7 +268,7 @@ class DatabaseOperations(BaseDatabaseOperations):
             if self.connection.mysql_is_mariadb:
                 # MariaDB includes the microsecond component in TIME_TO_SEC as
                 # a decimal. MySQL returns an integer without microseconds.
-                return '((TIME_TO_SEC(%(lhs)s) - TIME_TO_SEC(%(rhs)s)) * 1000000)' % {
+                return 'CAST((TIME_TO_SEC(%(lhs)s) - TIME_TO_SEC(%(rhs)s)) * 1000000 AS SIGNED)' % {
                     'lhs': lhs_sql, 'rhs': rhs_sql
                 }, lhs_params + rhs_params
             return (