diff --git a/bob/io/base/__init__.py b/bob/io/base/__init__.py
index da1b8abbc5af95f28496c8f5aca9269425290b29..7d4d6f5e6203a35aa4766aa9d6232b092b75b8d8 100644
--- a/bob/io/base/__init__.py
+++ b/bob/io/base/__init__.py
@@ -86,8 +86,8 @@ def open_file(filename):
         # Checking for gray scaled images
         if (
             img.ndim > 2
-            and np.allclose(img[:, :, 0], img[:, :, 1])
-            and np.allclose(img[:, :, 0], img[:, :, 2])
+            and np.array_equal(img[:, :, 0], img[:, :, 1])
+            and np.array_equal(img[:, :, 0], img[:, :, 2])
         ):
             img = img[:, :, 0]
         return img