diff --git a/ChangeLog b/ChangeLog
index 24679b5..debacf5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,6 @@
 User johns
 
+    Fix bug: audio increments invalid audio PTS.
     Fix bug: dvd plugin not working.
     Fix bug: used frame-> instead of video_ctx-> for old libav/ffmpeg.
 
diff --git a/audio.c b/audio.c
index 5d470f6..f7c208a 100644
--- a/audio.c
+++ b/audio.c
@@ -290,9 +290,11 @@ static int AlsaAddToRingbuffer(const void *samples, int count)
 	// FIXME: should skip more, longer skip, but less often?
     }
     // Update audio clock
-    AudioPTS +=
-	((int64_t) count * 90000) / (AudioSampleRate * AudioChannels *
-	AudioBytesProSample);
+    if (AudioPTS != INT64_C(0x8000000000000000)) {
+	AudioPTS +=
+	    ((int64_t) count * 90000) / (AudioSampleRate * AudioChannels *
+	    AudioBytesProSample);
+    }
 
     if (!AudioRunning) {
 	if (AlsaStartThreshold < RingBufferUsedBytes(AlsaRingBuffer)) {
@@ -1275,9 +1277,11 @@ static int OssAddToRingbuffer(const void *samples, int count)
 	// FIXME: should skip more, longer skip, but less often?
     }
     // Update audio clock
-    AudioPTS +=
-	((int64_t) count * 90000) / (AudioSampleRate * AudioChannels *
-	AudioBytesProSample);
+    if (AudioPTS != INT64_C(0x8000000000000000)) {
+	AudioPTS +=
+	    ((int64_t) count * 90000) / (AudioSampleRate * AudioChannels *
+	    AudioBytesProSample);
+    }
 
     if (!AudioRunning) {
 	if (OssStartThreshold < RingBufferUsedBytes(OssRingBuffer)) {