diff --git a/serial/serbridge.c b/serial/serbridge.c
index e1f3fdc..9f782bb 100644
--- a/serial/serbridge.c
+++ b/serial/serbridge.c
@@ -23,7 +23,7 @@ static struct espconn serbridgeConn2; // programming port
 static esp_tcp serbridgeTcp1, serbridgeTcp2;
 static int8_t mcu_reset_pin, mcu_isp_pin;
 
-extern uint8_t slip_disabled;   // disable slip to allow flashing of attached MCU
+uint8_t in_mcu_flashing;   // for disabling slip during MCU flashing
 
 void (*programmingCB)(char *buffer, short length) = NULL;
 
@@ -124,14 +124,14 @@ telnetUnwrap(uint8_t *inBuf, int len, uint8_t state)
 #ifdef SERBR_DBG
         else { os_printf("MCU isp: no pin\n"); }
 #endif
-        slip_disabled++;
+        in_mcu_flashing++;
         break;
       case RTS_OFF:
         if (mcu_isp_pin >= 0) {
           GPIO_OUTPUT_SET(mcu_isp_pin, 1);
           os_delay_us(100L);
         }
-        if (slip_disabled > 0) slip_disabled--;
+        if (in_mcu_flashing > 0) in_mcu_flashing--;
         break;
       }
       state = TN_end;
@@ -222,7 +222,7 @@ serbridgeRecvCb(void *arg, char *data, unsigned short len)
     //if (mcu_isp_pin >= 0) GPIO_OUTPUT_SET(mcu_isp_pin, 1);
     os_delay_us(1000L); // wait a millisecond before writing to the UART below
     conn->conn_mode = cmPGM;
-    slip_disabled++; // disable SLIP so it doesn't interfere with flashing
+    in_mcu_flashing++; // disable SLIP so it doesn't interfere with flashing
 #ifdef SKIP_AT_RESET
     serledFlash(50); // short blink on serial LED
     return;
@@ -355,7 +355,7 @@ serbridgeUartCb(char *buf, short length)
 {
   if (programmingCB) {
     programmingCB(buf, length);
-  } else if (!flashConfig.slip_enable || slip_disabled > 0) {
+  } else if (!flashConfig.slip_enable || in_mcu_flashing > 0) {
     //os_printf("SLIP: disabled got %d\n", length);
     console_process(buf, length);
   } else {
@@ -505,7 +505,7 @@ serbridgeInit(int port1, int port2)
   espconn_regist_time(&serbridgeConn2, SER_BRIDGE_TIMEOUT, 0);
 }
 
-int  ICACHE_FLASH_ATTR serbridgeInProgramming()
+int  ICACHE_FLASH_ATTR serbridgeInMCUFlashing()
 {
-  return slip_disabled;
+  return in_mcu_flashing;
 }
diff --git a/serial/serbridge.h b/serial/serbridge.h
index c24953c..ed661e1 100644
--- a/serial/serbridge.h
+++ b/serial/serbridge.h
@@ -36,7 +36,7 @@ void ICACHE_FLASH_ATTR serbridgeInitPins(void);
 void ICACHE_FLASH_ATTR serbridgeUartCb(char *buf, short len);
 void ICACHE_FLASH_ATTR serbridgeReset();
 
-int  ICACHE_FLASH_ATTR serbridgeInProgramming();
+int  ICACHE_FLASH_ATTR serbridgeInMCUFlashing();
 
 // callback when receiving UART chars when in programming mode
 extern void (*programmingCB)(char *buffer, short length);
diff --git a/serial/slip.c b/serial/slip.c
index 76d8f97..2f15186 100644
--- a/serial/slip.c
+++ b/serial/slip.c
@@ -13,8 +13,6 @@
 #define DBG(format, ...) do { } while(0)
 #endif
 
-uint8_t slip_disabled;   // temporarily disable slip to allow flashing of attached MCU
-
 extern void ICACHE_FLASH_ATTR console_process(char *buf, short len);
 
 // This SLIP parser tries to conform to RFC 1055 https://tools.ietf.org/html/rfc1055.
diff --git a/web-server/web-server.c b/web-server/web-server.c
index 4689014..0d323a2 100644
--- a/web-server/web-server.c
+++ b/web-server/web-server.c
@@ -167,7 +167,7 @@ static int ICACHE_FLASH_ATTR WEB_handleJSONRequest(HttpdConnData *connData)
 		errorResponse(connData, 500, "No MCU callback is registered!");
 		return HTTPD_CGI_DONE;
 	}
-	if( serbridgeInProgramming() )
+	if( serbridgeInMCUFlashing() )
 	{
 		errorResponse(connData, 500, "Slip disabled at uploading program onto the MCU!");
 		return HTTPD_CGI_DONE;