diff --git a/main/file.c b/main/file.c
index 1bec4fca48..73387a2ff9 100644
--- a/main/file.c
+++ b/main/file.c
@@ -665,9 +665,17 @@ static enum fsread_res ast_readaudio_callback(struct ast_filestream *s)
 	}
 	if (whennext != s->lasttimeout) {
 #ifdef HAVE_ZAPTEL
-		if (s->owner->timingfd > -1)
-			ast_settimeout(s->owner, whennext, ast_fsread_audio, s);
-		else
+		if (s->owner->timingfd > -1) {
+			int zap_timer_samples = whennext;
+			int rate;
+			/* whennext is in samples, but zaptel timers operate in 8 kHz samples. */
+			if ((rate = ast_format_rate(s->fmt->format)) != 8000) {
+				float factor;
+				factor = ((float) rate) / ((float) 8000.0); 
+				zap_timer_samples = (int) ( ((float) zap_timer_samples) / factor );
+			}
+			ast_settimeout(s->owner, zap_timer_samples, ast_fsread_audio, s);
+		} else
 #endif		
 			s->owner->streamid = ast_sched_add(s->owner->sched, 
 				whennext / (ast_format_rate(s->fmt->format) / 1000), ast_fsread_audio, s);