diff --git a/rei_toolbox/dubstrip.py b/rei_toolbox/dubstrip.py
index 5fe4792..7e129a3 100644
--- a/rei_toolbox/dubstrip.py
+++ b/rei_toolbox/dubstrip.py
@@ -34,8 +34,8 @@ def has_audio_not_in_lang(meta: Dict[str, Any], lang: str) -> bool:
 
 def make_dubstrip_command(
     file: Path, outfile: Path, meta: Dict[str, Any], keep_lang: str
-) -> List[Union[str, Path]]:
-    cmd = ["ffmpeg", "-nostdin", "-i", file, "-map", "0"]
+) -> List[str]:
+    cmd = ["ffmpeg", "-nostdin", "-i", f"file:{file}", "-map", "0"]
 
     for stream in meta["streams"]:
         if stream["codec_type"] == "audio":
@@ -44,7 +44,7 @@ def make_dubstrip_command(
                 cmd += ["-map", f"-0:{idx}"]
 
     # Only remux; don't recode.
-    cmd += ["-c", "copy", outfile]
+    cmd += ["-c", "copy", f"file:{outfile}"]
 
     return cmd
 
diff --git a/tests/test_dubstrip.py b/tests/test_dubstrip.py
index 6ad08cc..8d1aa92 100644
--- a/tests/test_dubstrip.py
+++ b/tests/test_dubstrip.py
@@ -28,13 +28,13 @@ class DubstripTestCase(unittest.TestCase):
                 "ffmpeg",
                 "-nostdin",
                 "-i",
-                fin,
+                "file:a.mkv",
                 "-map",
                 "0",
                 "-map",
                 "-0:1",
                 "-c",
                 "copy",
-                fout,
+                "file:b.mkv",
             ],
         )