diff --git a/adafruit_vl53l1x.py b/adafruit_vl53l1x.py
index 32b88ac..58ec7ed 100644
--- a/adafruit_vl53l1x.py
+++ b/adafruit_vl53l1x.py
@@ -250,7 +250,7 @@ def timing_budget(self, val):
             reg_vals = TB_LONG_DIST
         if reg_vals is None:
             raise RuntimeError("Unknown distance mode.")
-        if val not in reg_vals.keys():
+        if val not in reg_vals:
             raise ValueError("Invalid timing budget.")
         self._write_register(_RANGE_CONFIG__TIMEOUT_MACROP_A_HI, reg_vals[val][0])
         self._write_register(_RANGE_CONFIG__TIMEOUT_MACROP_B_HI, reg_vals[val][1])