diff --git a/caiman/utils/visualization.py b/caiman/utils/visualization.py
index cceb58f59..707781d0e 100644
--- a/caiman/utils/visualization.py
+++ b/caiman/utils/visualization.py
@@ -401,7 +401,6 @@ def get_contours(A, dims, thr=0.9, thr_method='nrg', swap_dim=False, slice_dim:
     if 'csc_matrix' not in str(type(A)):
         A = csc_matrix(A)
     d, nr = np.shape(A)
-    d1, d2 = dims[:2]
 
     coordinates = []
 
@@ -443,6 +442,7 @@ def get_contours(A, dims, thr=0.9, thr_method='nrg', swap_dim=False, slice_dim:
 
         def get_slice_coords(B: np.ndarray) -> np.ndarray:
             """Get contour coordinates for a 2D slice"""
+            d1, d2 = B.shape
             vertices = find_contours(B.T, thr)
             # this fix is necessary for having disjoint figures and borders plotted correctly
             v = np.atleast_2d([np.nan, np.nan])
@@ -451,8 +451,8 @@ def get_slice_coords(B: np.ndarray) -> np.ndarray:
                 if num_close_coords < 2:
                     if num_close_coords == 0:
                         # case angle
-                        newpt = np.round(vtx[-1, :] / [d2, d1]) * [d2, d1]
-                        vtx = np.concatenate((vtx, newpt[np.newaxis, :]), axis=0)
+                        newpt = np.round(np.mean(vtx[[0, -1], :], axis=0) / [d2, d1]) * [d2, d1]
+                        vtx = np.concatenate((newpt[np.newaxis, :], vtx, newpt[np.newaxis, :]), axis=0)
                     else:
                         # case one is border
                         vtx = np.concatenate((vtx, vtx[0, np.newaxis]), axis=0)