diff --git a/src/genomicranges/GenomicRangesList.py b/src/genomicranges/GenomicRangesList.py
index ae5b0b7..e3b8828 100644
--- a/src/genomicranges/GenomicRangesList.py
+++ b/src/genomicranges/GenomicRangesList.py
@@ -426,7 +426,7 @@ def set_names(
             or as a reference to the (in-place-modified) original.
         """
         if names is not None:
-            _validate_optional_attrs(None, names, len(self))
+            _validate_optional_attrs(self.get_mcols(), names, len(self))
 
             if not isinstance(names, ut.Names):
                 names = ut.Names(names)
diff --git a/tests/test_grl_initialize.py b/tests/test_grl_initialize.py
index f3e552f..4215259 100644
--- a/tests/test_grl_initialize.py
+++ b/tests/test_grl_initialize.py
@@ -42,3 +42,13 @@ def test_create_grl_should_fail():
 def test_empty_grl():
     grl = GenomicRangesList.empty(n=100)
     assert isinstance(grl, GenomicRangesList)
+
+
+def test_grl_set_names():
+    grl = GenomicRangesList(ranges=[a, b], names=["a", "b"])
+
+    grl_replace_names = grl.set_names(["aa", "bb"])
+
+    assert grl_replace_names is not None
+    assert isinstance(grl_replace_names, GenomicRangesList)
+    assert list(grl.get_names()) == ["a", "b"]