diff --git a/cores/esp8266/core_esp8266_phy.c b/cores/esp8266/core_esp8266_phy.c
index 130c5e36d..53c781113 100644
--- a/cores/esp8266/core_esp8266_phy.c
+++ b/cores/esp8266/core_esp8266_phy.c
@@ -198,7 +198,7 @@ static uint8_t phy_init_data[128] =
     
     // vdd33_const
     // the voltage of PA_VDD
-    // x=0xff: it can measure VDD33, 
+    // x=0xff: it can measure VDD33,
     // 18<=x<=36: use input voltage,  
     // the value is voltage*10, 33 is 3.3V, 30 is 3.0V,
     // x<18 or x>36: default voltage is 3.3V