diff --git a/python/tests/test_topology.py b/python/tests/test_topology.py
index 43b382c4bb..0a0988bf92 100644
--- a/python/tests/test_topology.py
+++ b/python/tests/test_topology.py
@@ -8654,12 +8654,12 @@ def verify_extend_edges(self, ts):
 
         for e in ets.edges():
             # e should be in old_edges,
-            # but with expanded limits
+            # but with modified limits
             k = (e.parent, e.child)
             assert k in old_edges
             overlaps = False
             for (l, r) in old_edges[k]:
-                if (l >= e.left) and (r <= e.right):
+                if (l <= e.right) and (r >= e.left):
                     overlaps = True
             assert overlaps
 
@@ -8774,8 +8774,20 @@ def test_simple_ex(self):
             assert t.parent(8) == 6
         self.verify_extend_edges(ts)
 
-    def test_extend_edges(self):
-        tables = wf.wf_sim(5, 20, deep_history=False, seed=3)
+    def test_wright_fisher_trees(self):
+        tables = wf.wf_sim(N=5, ngens=20, deep_history=False, seed=3)
         tables.sort()
         ts = tables.tree_sequence().simplify()
         self.verify_extend_edges(ts)
+
+    def test_wright_fisher_trees_unsimplified(self):
+        tables = wf.wf_sim(N=6, ngens=22, deep_history=False, seed=4)
+        tables.sort()
+        ts = tables.tree_sequence()
+        self.verify_extend_edges(ts)
+
+    def test_wright_fisher_trees_with_history(self):
+        tables = wf.wf_sim(N=8, ngens=15, deep_history=True, seed=5)
+        tables.sort()
+        ts = tables.tree_sequence()
+        self.verify_extend_edges(ts)