diff --git a/stytra/stimulation/stimuli/visual.py b/stytra/stimulation/stimuli/visual.py
index 1cb7f139..9655f2ec 100644
--- a/stytra/stimulation/stimuli/visual.py
+++ b/stytra/stimulation/stimuli/visual.py
@@ -539,8 +539,8 @@ def draw_block(self, p, point, w, h):
         p.setRenderHint(QPainter.Antialiasing)
         p.setBrush(QBrush(QColor(*self.color)))
         p.drawRect(
-            point.x(),
-            point.y(),
+            int(point.x()),
+            int(point.y()),
             int(
                 self.grating_period
                 / (2 * max(self._experiment.calibrator.mm_px, 0.0001))
diff --git a/stytra/utilities.py b/stytra/utilities.py
index b1adcc26..45bc34bd 100644
--- a/stytra/utilities.py
+++ b/stytra/utilities.py
@@ -132,7 +132,7 @@ def prepare_json(it, **kwargs):
     if isinstance(it, list):
         return [prepare_json(el, **kwargs) for el in it]
     if isinstance(it, np.generic):
-        return np.asscalar(it)
+        return it.item()
     if isinstance(it, datetime):
         if kwargs.get("convert_datetime", False):
             return it.isoformat()