diff --git a/mysql-test/r/func_sapdb.result b/mysql-test/r/func_sapdb.result
index 29ceb6ecaa4..124b20e9b46 100644
--- a/mysql-test/r/func_sapdb.result
+++ b/mysql-test/r/func_sapdb.result
@@ -240,9 +240,7 @@ a
 10000
 select microsecond(19971231235959.01) as a;
 a
-0
-Warnings:
-Warning	1292	Truncated incorrect time value: '19971231235959.01'
+10000
 select date_add("1997-12-31",INTERVAL "10.09" SECOND_MICROSECOND) as a;
 a
 1997-12-31 00:00:10.090000
diff --git a/mysql-test/r/func_time.result b/mysql-test/r/func_time.result
index 1f52076f3d2..ac0ad0af066 100644
--- a/mysql-test/r/func_time.result
+++ b/mysql-test/r/func_time.result
@@ -1050,6 +1050,10 @@ H
 select last_day('0000-00-00');
 last_day('0000-00-00')
 NULL
+select isnull(week(now() + 0)), isnull(week(now() + 0.2)),
+week(20061108), week(20061108.01), week(20061108085411.000002);
+isnull(week(now() + 0))	isnull(week(now() + 0.2))	week(20061108)	week(20061108.01)	week(20061108085411.000002)
+0	0	45	45	45
 End of 4.1 tests
 explain extended select timestampdiff(SQL_TSI_WEEK, '2001-02-01', '2001-05-01') as a1,
 timestampdiff(SQL_TSI_FRAC_SECOND, '2001-02-01 12:59:59.120000', '2001-05-01 12:58:58.119999') as a2;
diff --git a/mysql-test/t/func_time.test b/mysql-test/t/func_time.test
index ebaa6d84bd3..344acf65df3 100644
--- a/mysql-test/t/func_time.test
+++ b/mysql-test/t/func_time.test
@@ -571,6 +571,13 @@ union
 
 select last_day('0000-00-00');
 
+#
+# Bug 23616: datetime functions with double argumets
+#
+
+select isnull(week(now() + 0)), isnull(week(now() + 0.2)),
+  week(20061108), week(20061108.01), week(20061108085411.000002);
+
 --echo End of 4.1 tests
 
 explain extended select timestampdiff(SQL_TSI_WEEK, '2001-02-01', '2001-05-01') as a1,
diff --git a/sql-common/my_time.c b/sql-common/my_time.c
index dcbd2eacdc1..aeb3aaec675 100644
--- a/sql-common/my_time.c
+++ b/sql-common/my_time.c
@@ -207,7 +207,7 @@ str_to_datetime(const char *str, uint length, MYSQL_TIME *l_time,
   digits= (uint) (pos-str);
   start_loop= 0;                                /* Start of scan loop */
   date_len[format_position[0]]= 0;              /* Length of year field */
-  if (pos == end)
+  if (pos == end || *pos == '.')
   {
     /* Found date in internal format (only numbers like YYYYMMDD) */
     year_length= (digits == 4 || digits == 8 || digits >= 14) ? 4 : 2;