diff --git a/main/dsp.c b/main/dsp.c
index 4ad255c3fe..ecb1365c68 100644
--- a/main/dsp.c
+++ b/main/dsp.c
@@ -502,7 +502,7 @@ static void ast_mf_detect_init (mf_detect_state_t *s, unsigned int sample_rate)
 	int i;
 	s->hits[0] = s->hits[1] = s->hits[2] = s->hits[3] = s->hits[4] = 0;
 	for (i = 0;  i < 6;  i++) {
-		goertzel_init (&s->tone_out[i], mf_tones[i], MF_SIZE, sample_rate);
+		goertzel_init (&s->tone_out[i], mf_tones[i], MF_GSIZE, sample_rate);
 	}
 	s->current_sample = 0;
 	s->current_hit = 0;