diff --git a/app.py b/app.py
index 4b91552..19af596 100644
--- a/app.py
+++ b/app.py
@@ -22,9 +22,13 @@ def convert_to_wav(file_name: str):
     assert extension != "wav"
 
     print(f"{extension=}")
-    command = f"tape2wav {file_name} ${output}.wav"
+    command = [
+        "tape2wav",
+        file_name,
+        f"${output}.wav",
+    ]
     try:
-        check_call(command.split())
+        check_call(command)
     except CalledProcessError as exc:
         print(f"tape2wav failed: {exc.output=}\n{exc.stderr=}")
         raise