diff --git a/web.py b/web.py
index 36a6b81..a8d2651 100644
--- a/web.py
+++ b/web.py
@@ -272,6 +272,15 @@ class _Handler(BaseHTTPRequestHandler):
         if path is None:
             return
 
+        status_path = Path(self.recordings_dir) / 'status.json'
+        try:
+            with open(status_path) as fh:
+                if filename in set(json.load(fh).get('active', [])):
+                    self._json_err(409, 'File is currently being recorded — analysis unavailable until recording stops')
+                    return
+        except Exception:
+            pass
+
         ext = path.suffix.lower()
         if ext == '.wav':
             result = analyze_wav(path, threshold=self.threshold)
@@ -691,7 +700,12 @@ async function load() {
       const abtn = document.createElement('button');
       abtn.textContent = 'Analyse';
       abtn.setAttribute('aria-label', `Analyse loudness of ${f.name}`);
-      abtn.addEventListener('click', () => analyse(f.name, cell, abtn));
+      if (isRec) {
+        abtn.disabled = true;
+        abtn.title = 'Recording in progress — analyse after recording stops';
+      } else {
+        abtn.addEventListener('click', () => analyse(f.name, cell, abtn));
+      }
       cell.appendChild(abtn);
     }