diff --git a/libs/freetdm/src/libteletone_detect.c b/libs/freetdm/src/libteletone_detect.c
index 004aac3e58..c0e75e3bfd 100644
--- a/libs/freetdm/src/libteletone_detect.c
+++ b/libs/freetdm/src/libteletone_detect.c
@@ -217,7 +217,7 @@ int teletone_multi_tone_detect (teletone_multi_tone_t *mt,
 	float eng_sum = 0, eng_all[TELETONE_MAX_TONES];
 	int gtest = 0, see_hit = 0;
 
-	for (sample = 0;  sample < samples;	 sample = limit) {
+	for (sample = 0; sample <= 0 && sample < samples; sample = limit) {
 		mt->total_samples++;
 
 		if ((samples - sample) >= (mt->min_samples - mt->current_sample)) {