diff --git a/barista/barista.ino b/barista/barista.ino
index c0f3388..4836ab1 100644
--- a/barista/barista.ino
+++ b/barista/barista.ino
@@ -77,6 +77,7 @@ struct state {
 	unsigned long hot_t0;
 
 	int ntc_i; /* Next available place */
+	int ntc_n; /* Samples in array */
 	float ntc_R;
 	float ntc_last_T;
 	float ntc_array_T[MAX_SAMPLES];
@@ -132,12 +133,14 @@ void proc_ntc(struct state *state, const struct input *input)
 	state->ntc_array_T[state->ntc_i++] = state->ntc_last_T;
 	if (state->ntc_i >= MAX_SAMPLES)
 		state->ntc_i = 0;
+	if (state->ntc_n < MAX_SAMPLES)
+		state->ntc_n++;
 
 	float avg = 0;
-	for (int i = 0; i < MAX_SAMPLES; i++)
+	for (int i = 0; i < state->ntc_n; i++)
 		avg += state->ntc_array_T[i];
 
-	state->ntc_T = avg / MAX_SAMPLES;
+	state->ntc_T = avg / state->ntc_n;
 
 	overheat_input(&state->overheat, millis(), state->ntc_T);
 }