diff --git a/c2cwsgiutils/acceptance/image.py b/c2cwsgiutils/acceptance/image.py
index a08de53b5..95cc79ac0 100644
--- a/c2cwsgiutils/acceptance/image.py
+++ b/c2cwsgiutils/acceptance/image.py
@@ -125,7 +125,7 @@ def check_image(
         assert ((0 < mask) & (mask < 255)).sum() == 0, "Mask should be only black and white image"
 
         # Convert to boolean
-        mask = mask != 0
+        mask = mask == 0
 
         assert (
             mask.shape[0] == image_to_check.shape[0] and mask.shape[1] == image_to_check.shape[1]
@@ -148,6 +148,7 @@ def check_image(
         assert (
             expected.shape[0] == mask.shape[0] and expected.shape[1] == mask.shape[1]
         ), f"Mask and expected image should have the same shape ({mask.shape} != {expected.shape})"
+        expected[mask] = [255, 255, 255]
 
     assert (
         expected.shape == image_to_check.shape
diff --git a/c2cwsgiutils/acceptance/screenshot.js b/c2cwsgiutils/acceptance/screenshot.js
index 9661df891..5d29c3da7 100644
--- a/c2cwsgiutils/acceptance/screenshot.js
+++ b/c2cwsgiutils/acceptance/screenshot.js
@@ -49,13 +49,13 @@ const options = program.opts();
     }
   });
 
-  await page.goto(options.url, { timeout: 60000 });
-
   await page.setViewport({
     width: parseInt(options.width),
     height: parseInt(options.height),
   });
-  await page.waitForTimeout(parseInt(options.sleep));
+  await page.goto(options.url, { timeout: 60000 });
+
+  await new Promise((r) => setTimeout(r, parseInt(options.sleep)));
   await page.screenshot({
     path: options.output,
     clip: { x: 0, y: 0, width: parseInt(options.width), height: parseInt(options.height) },