diff --git a/model_server/base/roiset.py b/model_server/base/roiset.py
index 7c3b3ae907a0ae8ccc1e709cfa2ae8f5b8e58ed8..936b53682821f015f46e2dcb07c9ffcb6f2455db 100644
--- a/model_server/base/roiset.py
+++ b/model_server/base/roiset.py
@@ -172,7 +172,7 @@ class RoiSet(object):
         df['rel_x1'] = df.x1 - df.ebb_x0
 
         assert np.all(df['rel_x1'] <= (df['ebb_x1'] - df['ebb_x0']))
-        assert np.all(df['rel_y1'] <= (df['ebb_x1'] - df['ebb_x0']))
+        assert np.all(df['rel_y1'] <= (df['ebb_y1'] - df['ebb_y0']))
 
         df['slice'] = df.apply(
             lambda r: