diff --git a/mrcnn/utils.py b/mrcnn/utils.py
index 7e1c9d2832f6fad31c4cfd8cb735db194726dfcb..f65a56de8f6f5f465465fda23fd4b27aa8ed32e6 100644
--- a/mrcnn/utils.py
+++ b/mrcnn/utils.py
@@ -102,8 +102,8 @@ def compute_overlaps_masks(masks1, masks2):
     """
     
     # If either set of masks is empty return empty result
-    if masks1.shape[0] == 0 or masks2.shape[0] == 0:
-        return np.zeros((masks1.shape[0], masks2.shape[-1]))
+    if masks1.shape[-1] == 0 or masks2.shape[-1] == 0:
+        return np.zeros((masks1.shape[-1], masks2.shape[-1]))
     # flatten masks and compute their areas
     masks1 = np.reshape(masks1 > .5, (-1, masks1.shape[-1])).astype(np.float32)
     masks2 = np.reshape(masks2 > .5, (-1, masks2.shape[-1])).astype(np.float32)