diff --git a/ffcuesplitter/ffmpeg.py b/ffcuesplitter/ffmpeg.py
index d95ed06..a39231a 100644
--- a/ffcuesplitter/ffmpeg.py
+++ b/ffcuesplitter/ffmpeg.py
@@ -197,9 +197,11 @@ def run_ffmpeg_command_with_progress(self, cmd, seconds):
 
                     for output in proc.stdout:
                         if "out_time_ms" in output.strip():
-                            s_processed = int(output.split('=')[1]) / 1_000_000
-                            percent = s_processed / seconds * 100
-                            progbar.update(round(percent) - progbar.n)
+                            out_time_ms_val = output.split('=')[1].strip()
+                            if out_time_ms_val.isdigit():
+                                s_processed = int(out_time_ms_val) / 1_000_000
+                                percent = s_processed / seconds * 100
+                                progbar.update(round(percent) - progbar.n)
 
                     if proc.wait():  # error
                         logging.error("Popen proc.wait() Exit status %s",