diff --git a/bincio/serve/server.py b/bincio/serve/server.py
index 7126b9c..e4d190e 100644
--- a/bincio/serve/server.py
+++ b/bincio/serve/server.py
@@ -612,6 +612,14 @@ async def save_athlete(
 _SUPPORTED_SUFFIXES = {".fit", ".gpx", ".tcx", ".fit.gz", ".gpx.gz", ".tcx.gz"}
 
 
+def _file_suffix(name: str) -> str:
+    """Return the effective suffix, including .gz double-extension."""
+    p = Path(name.lower())
+    if p.suffix == ".gz":
+        return p.stem.rsplit(".", 1)[-1].join([".", ".gz"]) if "." in p.stem else ".gz"
+    return p.suffix
+
+
 @app.post("/api/upload")
 async def upload_activity(
     files: list[UploadFile] = File(...),
diff --git a/site/src/layouts/Base.astro b/site/src/layouts/Base.astro
index 7300983..b20cd7f 100644
--- a/site/src/layouts/Base.astro
+++ b/site/src/layouts/Base.astro
@@ -285,7 +285,7 @@ try {
             class="border-2 border-dashed border-zinc-700 rounded-lg p-8 text-center text-zinc-500 text-sm cursor-pointer hover:border-zinc-500 hover:text-zinc-300 transition-colors"
           >
             <div id="upload-label">Drop FIT, GPX, TCX, or activities.csv<br/>or click to browse</div>
-            <input id="upload-input" type="file" accept=".fit,.gpx,.tcx,.fit.gz,.gpx.gz,.tcx.gz,.csv" class="hidden" multiple />
+            <input id="upload-input" type="file" accept=".fit,.gpx,.tcx,.fit.gz,.gpx.gz,.tcx.gz,.csv,application/gpx+xml,application/vnd.garmin.tcx+xml,application/octet-stream" class="hidden" multiple />
           </div>
           <label class="flex items-start gap-2 mt-3 cursor-pointer group">
             <input