diff --git a/firmware/src/board/gpio.rs b/firmware/src/board/gpio.rs
index 6f8349f..8dda7ca 100644
--- a/firmware/src/board/gpio.rs
+++ b/firmware/src/board/gpio.rs
@@ -21,7 +21,7 @@ macro_rules! def_gpio {
             }
             fn into_input(self) -> GpioInput<Self> {
                 let gpio = unsafe { &*tm4c129x::$PORT::ptr() };
-                gpio.dir.modify(|_, w| w.dir().bits(1 << $idx));
+                gpio.dir.modify(|r, w| w.dir().bits(r.dir().bits() & !(1 << $idx)));
                 gpio.den.modify(|_, w| w.den().bits(1 << $idx));
                 GpioInput(self)
             }