diff --git a/components/esp8266/driver/i2c.c b/components/esp8266/driver/i2c.c
index d5805d14..41b55945 100644
--- a/components/esp8266/driver/i2c.c
+++ b/components/esp8266/driver/i2c.c
@@ -500,7 +500,7 @@ static void i2c_master_cmd_begin_static(i2c_port_t i2c_num)
                     i2c_master_set_dc(i2c_num, i2c_last_state[i2c_num]->sda, 0);
 
                     for (i = 7; i >= 0; i--) {
-                        if (cmd->byte_num == 1) {
+                        if (cmd->byte_num == 1 && cmd->data == NULL) {
                             dat = (cmd->byte_cmd) >> i;
                         } else {
                             dat = ((uint8_t) * (cmd->data + len)) >> i;
@@ -615,4 +615,4 @@ esp_err_t i2c_master_cmd_begin(i2c_port_t i2c_num, i2c_cmd_handle_t cmd_handle,
         return ESP_FAIL;
     }
 
-}
\ No newline at end of file
+}