diff --git a/src/wiiboard.c b/src/wiiboard.c
index dd6fd04..6085214 100644
--- a/src/wiiboard.c
+++ b/src/wiiboard.c
@@ -110,12 +110,14 @@ void wii_board_disconnected(struct wii_board_t* wb) {
 
 static float do_interpolate(uint16_t raw, uint16_t cal[3]) {
 #define WIIBOARD_MIDDLE_CALIB 17.0f
-	if (raw < cal[1]) {
+	if (raw < cal[0]) {
+		return 0.0f;
+	} else if (raw < cal[1]) {
 		return ((raw-cal[0]) * WIIBOARD_MIDDLE_CALIB)/(float)(cal[1] - cal[0]);
-	} else if (raw > cal[1]) {
+	} else if (raw < cal[2]) {
 		return ((raw-cal[1]) * WIIBOARD_MIDDLE_CALIB)/(float)(cal[2] - cal[1]) + WIIBOARD_MIDDLE_CALIB;
 	} else {
-		return WIIBOARD_MIDDLE_CALIB;
+		return WIIBOARD_MIDDLE_CALIB * 2.0f;
 	}
 }