diff --git a/daemon/codec.c b/daemon/codec.c
index fb69b2f30..17a1de118 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -1938,10 +1938,11 @@ static int packet_dtmf_fwd(struct codec_ssrc_handler *ch, struct transcode_packe
 		struct media_packet *mp)
 {
 	int payload_type = -1; // take from handler's output config
-	struct codec_ssrc_handler *output_ch = NULL;
-	struct codec_ssrc_handler *decoder_ch = NULL;
 
 	if (ch->handler->dtmf_scaler) {
+		struct codec_ssrc_handler *output_ch = NULL;
+		struct codec_ssrc_handler *decoder_ch = NULL;
+
 		// this is actually a DTMF -> PCM handler
 		// grab our underlying PCM transcoder
 		struct codec_handler *decoder_handler = __decoder_handler(ch->handler, mp);
@@ -1964,14 +1965,14 @@ static int packet_dtmf_fwd(struct codec_ssrc_handler *ch, struct transcode_packe
 		if (ch->dtmf_ts != packet->ts) {
 			// this is a new event
 			ch->dtmf_ts = packet->ts; // start TS
-			ch->last_dtmf_event_ts = 0; // last shifted FIFO PTS
+			ch->last_dtmf_event_ts = 0; // last DTMF event duration
 		}
 
-		unsigned long ts = output_ch->encoder->fifo_pts;
+		unsigned long ts = output_ch->encoder->next_pts / output_ch->encoder->def->clockrate_mult;
 		// roll back TS to start of event
 		ts -= ch->last_dtmf_event_ts;
 		// adjust to output RTP TS
-		unsigned long packet_ts = ts / output_ch->encoder->def->clockrate_mult + output_ch->first_ts;
+		unsigned long packet_ts = ts + output_ch->first_ts;
 
 		ilogs(transcoding, LOG_DEBUG, "Scaling DTMF packet timestamp and duration: TS %lu -> %lu "
 				"(%u -> %u)",
@@ -1986,18 +1987,18 @@ static int packet_dtmf_fwd(struct codec_ssrc_handler *ch, struct transcode_packe
 			dtmf->duration = htons(duration);
 
 			// shift forward our output RTP TS
-			output_ch->encoder->fifo_pts = ts + duration;
+			output_ch->encoder->next_pts = (ts + duration) * output_ch->encoder->def->clockrate_mult;
 			output_ch->encoder->packet_pts += (duration - ch->last_dtmf_event_ts) * output_ch->encoder->def->clockrate_mult;
 			ch->last_dtmf_event_ts = duration;
 		}
 		payload_type = ch->handler->dtmf_payload_type;
-	}
 
 skip:
-	if (output_ch)
-		obj_put(&output_ch->h);
-	if (decoder_ch)
-		obj_put(&decoder_ch->h);
+		if (output_ch)
+			obj_put(&output_ch->h);
+		if (decoder_ch)
+			obj_put(&decoder_ch->h);
+	}
 
 	char *buf = malloc(packet->payload->len + sizeof(struct rtp_header) + RTP_BUFFER_TAIL_ROOM);
 	memcpy(buf + sizeof(struct rtp_header), packet->payload->s, packet->payload->len);
diff --git a/lib/codeclib.c b/lib/codeclib.c
index 79e1e5dbc..e5c684f40 100644
--- a/lib/codeclib.c
+++ b/lib/codeclib.c
@@ -1285,11 +1285,17 @@ int encoder_input_data(encoder_t *enc, AVFrame *frame,
 			return -1;
 
 		if (enc->avpkt.size) {
+			// don't rely on the encoder producing steady timestamps,
+			// instead keep track of them ourselves based on the returned
+			// frame duration
+			enc->avpkt.pts = enc->next_pts;
+
 			if (enc->def->codec_type->encoder_got_packet)
 				enc->def->codec_type->encoder_got_packet(enc);
 
 			callback(enc, u1, u2);
 
+			enc->next_pts += enc->avpkt.duration;
 			enc->mux_dts = enc->avpkt.dts + 1; // min next expected dts
 
 			av_packet_unref(&enc->avpkt);
diff --git a/lib/codeclib.h b/lib/codeclib.h
index 7af12fdce..cda735ce9 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -240,6 +240,7 @@ struct encoder_s {
 	AVAudioFifo *fifo;
 	int64_t fifo_pts; // pts of first data in fifo
 	int64_t packet_pts; // first pts of data in packetizer buffer
+	int64_t next_pts; // next pts expected from the encoder
 	int ptime;
 	int bitrate;
 	int samples_per_frame; // for encoding