diff --git a/chainladder/core/slice.py b/chainladder/core/slice.py
index 96a47799..fd071245 100644
--- a/chainladder/core/slice.py
+++ b/chainladder/core/slice.py
@@ -431,7 +431,9 @@ def key_to_slice(self, key: _LabelKey) -> tuple[_AxisKey, _AxisKey, _AxisKey, _A
         return out
 
     def __setitem__(self, key: _LabelKey, values: int | float | TriangleSlicer) -> None:
-        super().__setitem__(cast(tuple[_AxisKey, _AxisKey, _AxisKey, _AxisKey], self.key_to_slice(key)), values)
+        raw_slice = self.key_to_slice(key)
+        contig_slice = [_LocBase._contig_slice(x) for x in raw_slice]
+        super().__setitem__(cast(tuple[_AxisKey, _AxisKey, _AxisKey, _AxisKey], contig_slice), values)
 
 class Ilocation(_LocBase):
     """
diff --git a/chainladder/core/tests/test_slicing.py b/chainladder/core/tests/test_slicing.py
index c4c2f5ef..b54ed49b 100644
--- a/chainladder/core/tests/test_slicing.py
+++ b/chainladder/core/tests/test_slicing.py
@@ -273,7 +273,29 @@ def test_loc_setitem_triangle_value(clrd: Triangle) -> None:
         tri.loc["Aegis Grp", "comauto"] = sub * 2
         assert tri.loc["Aegis Grp", "comauto"] == sub * 2
 
+def test_loc_setitem_partial_triangles(raa: Triangle) -> None:
+    """
+    Use Triangle.loc to set a few origin or develop period via a TriangleSlicer.
+
+    Parameters
+    ----------
+    raa: Triangle
+        The raa sample data set fixture.
 
+    Returns
+    -------
+    None
+
+    """
+    raa2 = raa * 2
+    raa_new = raa.copy()
+    raa_new.loc[:,:,:,:60] = raa2.loc[:,:,:,:60]
+    raa_new.loc[:,:,:,72:] = raa2.loc[:,:,:,72:]
+    assert raa_new == raa2
+    raa_new = raa.copy()
+    raa_new.loc[:,:,:'1984',:] = raa2.loc[:,:,:'1984',:]
+    raa_new.loc[:,:,'1985':,:] = raa2.loc[:,:,'1985':,:]
+    assert raa_new == raa2
 
 def test_invalid_iloc_sparse_assignment(prism) -> None:
     """