diff --git a/src/channels.rs b/src/channels.rs
index cfec178..20aa8e6 100644
--- a/src/channels.rs
+++ b/src/channels.rs
@@ -264,9 +264,9 @@ impl<'a> Channels<'a> {
         let samples = 50;
         let mut target_voltage = ElectricPotential::new::<volt>(0.0);
         for _ in 0..samples {
-            target_voltage = target_voltage + self.get_center(channel);
+            target_voltage += self.read_vref(channel);
         }
-        target_voltage = target_voltage / samples as f64;
+        target_voltage /= samples as f64;
         let mut start_value = 1;
         let mut best_error = ElectricPotential::new::<volt>(100.0);