diff --git a/afsk/telem.c b/afsk/telem.c
index 6cc19985..059083ee 100644
--- a/afsk/telem.c
+++ b/afsk/telem.c
@@ -126,7 +126,7 @@ struct SensorData read_sensor_data(struct SensorConfig sensor) {
 struct SensorConfig config_sensor(char *bus, int address,  int milliAmps) {
     struct SensorConfig data;
 	
-    printf("Bus number: %d \n", atoi(bus[strlen(bus) - 1]));
+    printf("Bus number: %d \n", atoi(bus[(strlen(bus)/sizeof(bus[0]) - 1]));
 	   
     FILE *i2cdetect = popen("timeout --preserve-status 5 i2cdetect -y 0", "r");
     pclose(i2cdetect);