diff --git a/gpio/gpio.c b/gpio/gpio.c
index bf2a5b7..6ea1440 100755
--- a/gpio/gpio.c
+++ b/gpio/gpio.c
@@ -69,7 +69,7 @@ char *usage = "Usage: gpio -v\n"
 	"       gpio [-p] <read/write/wb> ...\n"
 	"       gpio <read/write/aread/awritewb/pwm/clock/mode> ...\n"
 	"       gpio <toggle/blink> <pin>\n"
-	"       gpio readall/reset\n"
+	"       gpio readall/reset [-a|--all]\n"
 	"       gpio unexportall/exports\n"
 	"       gpio export/edge/unexport ...\n"
 	"       gpio wfi <pin> <mode>\n"