diff --git a/src/aare/common/autofocus_tools.py b/src/aare/common/autofocus_tools.py
index 6b60795a..06b05b72 100644
--- a/src/aare/common/autofocus_tools.py
+++ b/src/aare/common/autofocus_tools.py
@@ -20,7 +20,8 @@ def focus_measure_edges(gray: np.ndarray, mask: np.ndarray | None = None, verbos
     if strong.size == 0:
         return 0.0
     if verbose:
-        print(f"mask pixels: {mask.sum()}, "
+        mask_sum = mask.sum() if mask is not None else roi.size
+        print(f"mask pixels: {mask_sum}, "
               f"focus={strong.mean():.2f}"
               f"strong_size={strong.size}")