buf[0] = 0;             /* reg offset */
        buf[1] = BIN2BCD(dt->tm_sec);
        buf[2] = BIN2BCD(dt->tm_min);
-       buf[3] = BIN2BCD(dt->tm_hour) | (1 << 6);
+       buf[3] = BIN2BCD(dt->tm_hour);
        buf[4] = BIN2BCD(dt->tm_wday) + 1;
        buf[5] = BIN2BCD(dt->tm_mday);
        buf[6] = BIN2BCD(dt->tm_mon) + 1;
 
        /* Ensure that device is set in 24-hour mode */
        val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
-       if ((val >= 0) && (val & (1 << 6)) == 0)
+       if ((val >= 0) && (val & (1 << 6)))
                i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
-                                         val | (1 << 6));
+                                         val & 0x3f);
 }
 
 static int ds1337_detach_client(struct i2c_client *client)