diff --git a/condenser.py b/condenser.py
index 978cfdb..4213a09 100644
--- a/condenser.py
+++ b/condenser.py
@@ -302,15 +302,14 @@ def get_srt(subtitle_streams: List[dict], file_folder: str, filename: str, temp_
 
 
 def convert_sub_if_needed(sub_path: str, temp_dir: str) -> str:
-    sub_root, sub_ext = op.splitext(sub_path)
-    if sub_ext.lower() != ".srt":
-        srt_path = op.join(temp_dir, "out.srt")
-        sub_convert_cmd = [ffmpeg_cmd, "-i", sub_path, srt_path]
-        result = sp.run(sub_convert_cmd, capture_output=True)
-        if result.returncode != 0:
-            raise SubtitleError("Could not open subtitle file " + sub_path + ": " + str(result.stderr))
-    else:
-        srt_path = sub_path
+    srt_path = op.join(temp_dir, "out.srt")
+
+    # Run ffmpeg even if the format doesn't change, as srt files may contain non-standard markup that should be stripped
+    sub_convert_cmd = [ffmpeg_cmd, "-i", sub_path, "-c:s", "text", srt_path]
+    result = sp.run(sub_convert_cmd, capture_output=True)
+    if result.returncode != 0:
+        raise SubtitleError("Could not open subtitle file " + sub_path + ": " + str(result.stderr))
+
     return srt_path