diff --git a/lib/radio_esp8266.c b/lib/radio_esp8266.c
index 54c96bd..f2c82da 100644
--- a/lib/radio_esp8266.c
+++ b/lib/radio_esp8266.c
@@ -62,6 +62,31 @@ static void radio_esp8266_transmit(uint8_t* data, uint8_t length) {
 	}
 }
 
+/** transmit string to radio
+ *  @param[in] data data to transmit
+ *  @param[in] length length of data to transmit
+ */
+static void radio_esp8266_transmits(char* str) {
+	if (NULL == str) {
+		return;
+	}
+	const uint16_t length = strlen(str);
+	radio_esp8266_transmit((uint8_t*)str, length);
+}
+
+/** transmit string to radio
+ *  @param[in] data data to transmit
+ *  @param[in] length length of data to transmit
+ */
+static void radio_esp8266_transmit_at(char* at) {
+	if (NULL == at) {
+		return;
+	}
+	radio_esp8266_transmits("AT");
+	radio_esp8266_transmits(at);
+	radio_esp8266_transmits("\r\n");
+}
+
 void radio_esp8266_setup(void)
 {
 	// configure pins
@@ -93,7 +118,7 @@ void radio_esp8266_setup(void)
 	radio_esp8266_activity = false;
 	radio_esp8266_success = false;
 
-	radio_esp8266_transmit((uint8_t*)"AT\r\n", 4); // verify if module is present
+	radio_esp8266_transmit_at(""); // verify if module is present
 	while (!radio_esp8266_activity || !radio_esp8266_success) { // wait for response
 		__WFI(); // sleep until something happened
 	}
@@ -154,7 +179,7 @@ void radio_esp8266_send(uint8_t* data, uint8_t length)
 
 void radio_esp8266_close(void)
 {
-	radio_esp8266_transmit((uint8_t*)"AT+CIPCLOSE\r\n", 13); // send AT command to close established connection
+	radio_esp8266_transmit_at("+CIPCLOSE"); // send AT command to close established connection
 }
 
 /** USART interrupt service routine called when data has been transmitted or received */