diff --git a/cidr4_merger.py b/cidr4_merger.py
index b1fd20f..e4b9575 100644
--- a/cidr4_merger.py
+++ b/cidr4_merger.py
@@ -138,7 +138,7 @@ def merge_neighbors(
         new_nodes.remove(a)
         new_nodes.remove(b)
         new_nodes.append(parent)
-    return sort_nodes(nodes)
+    return sort_nodes(new_nodes)
 
 
 def find_neighbours_singles(groups: defaultdict) -> tuple[list, list]:
diff --git a/tests/test_cidr4_merger.py b/tests/test_cidr4_merger.py
index efb0925..12b8858 100644
--- a/tests/test_cidr4_merger.py
+++ b/tests/test_cidr4_merger.py
@@ -296,8 +296,29 @@ def test_find_neighbours_singles(
     )
 
 
-def test_merge_neighbors():
-    assert True
+def test_merge_neighbors__only_neighbours(nodes_only_neighbours):
+    new_nodes = merge_neighbors(
+        nodes_only_neighbours,
+        [
+            ((0, 2, 12, 0), (1073741824, 2, 3, 0)),
+            ((2147483648, 2, 1, 2147483648), (3221225472, 2, 2, 2147483648)),
+        ],
+    )
+    assert new_nodes == [
+        (0, 1, 15, 0),
+        (2147483648, 1, 3, 0),
+    ]
+
+
+def test_merge_neighbors__neighbours_n_singles(nodes_with_neighbours_n_singles):
+    new_nodes = merge_neighbors(
+        nodes_with_neighbours_n_singles,
+        [((0, 2, 12, 0), (1073741824, 2, 3, 0))],
+    )
+    assert new_nodes == [
+        (0, 1, 15, 0),
+        (2147483648, 2, 1, 2147483648),
+    ]
 
 
 # def test_merge_nodes_recursion():