diff --git a/app.py b/app.py
index 22ccaa3..4176398 100755
--- a/app.py
+++ b/app.py
@@ -77,20 +77,16 @@ def scan(id: int):
     if calibration_id is None:
         raise RuntimeError("Impossible de faire l'acquisition sans étalonnage")
 
-    return render_template('scan.html', object=object)
+    return render_template('scan.html', object=object, calibrated=True)
 
 
 @app.route('/scan-acquisition/<id>')
 def scan_existing(id: int):
     conn = db.get()
-    calibration_id = session.get('calibration_id', None)
+    calibrated = session.get('calibration_id', None) is not None
     acquisition = db.Acquisition.get_from_id(id, conn)
     object = acquisition.object(conn)
-
-    if calibration_id is None:
-        raise RuntimeError("Impossible de faire l'acquisition sans étalonnage")
-
-    return render_template('scan.html', object=object, acquisition=acquisition)
+    return render_template('scan.html', object=object, acquisition=acquisition, calibrated=calibrated)
 
 
 @app.route("/calibrate/")
diff --git a/templates/scan.html b/templates/scan.html
index 38064bd..9b74e59 100644
--- a/templates/scan.html
+++ b/templates/scan.html
@@ -9,7 +9,7 @@
         </div>
         <div class="field is-grouped is-grouped-multiline">
             <div class="control">
-                <button {% if acquisition and acquisition.validated %}disabled{% endif %} id="scan-button" class="button is-link">Lancer l'acquisition</button>
+                <button {% if not calibrated or (acquisition and acquisition.validated) %}disabled{% endif %} id="scan-button" class="button is-link" {% if acquisition and acquisition.validated %}title="Vous ne pouvez pas refaire cette acquisition car elle a été validée"{% elif not calibrated %}title="Étalonnez le scanner pour pouvoir lancer l'acquisition"{% endif %}>Lancer l'acquisition</button>
             </div>
         </div>
         <article id="error-container" class="message is-danger" style="display: none;">