diff --git a/odc/geo/crs.py b/odc/geo/crs.py
index 8553b69c..5401af0f 100644
--- a/odc/geo/crs.py
+++ b/odc/geo/crs.py
@@ -76,12 +76,12 @@ def _make_crs(
     return (crs, crs_str, epsg)
 
 
-def _make_crs_transform_key(from_crs, to_crs, always_xy):
-    return (id(from_crs), id(to_crs), always_xy)
+def _make_crs_transform_key(from_crs, to_crs, always_xy, force_over=False):
+    return (id(from_crs), id(to_crs), always_xy, force_over)
 
 
 @cachetools.cached({}, key=_make_crs_transform_key)
-def _make_crs_transform(from_crs: _CRS, to_crs: _CRS, always_xy: bool) -> Transformer:
+def _make_crs_transform(from_crs: _CRS, to_crs: _CRS, always_xy: bool, force_over: bool = False) -> Transformer:
     return Transformer.from_crs(from_crs, to_crs, always_xy=always_xy, force_over=force_over)
 
 
@@ -299,7 +299,7 @@ def crs_str(self) -> str:
         return self._str
 
     def transformer_to_crs(
-        self, other: "CRS", always_xy: bool = True
+        self, other: "CRS", always_xy: bool = True, force_over: bool = False
     ) -> Callable[[Any, Any], Tuple[Any, Any]]:
         """
         Build coordinate transformer to other projection.
@@ -318,7 +318,7 @@ def transformer_to_crs(
         """
 
         # pylint: disable=protected-access
-        tr = _make_crs_transform(self._crs, other._crs, always_xy=always_xy)
+        tr = _make_crs_transform(self._crs, other._crs, always_xy=always_xy, force_over=force_over)
 
         def result(x, y, **kw):
             rx, ry = tr.transform(x, y, **kw)  # pylint: disable=unpacking-non-sequence
diff --git a/odc/geo/overlap.py b/odc/geo/overlap.py
index 759b9116..036bb77d 100644
--- a/odc/geo/overlap.py
+++ b/odc/geo/overlap.py
@@ -103,7 +103,7 @@ def __init__(
         self._src = src
         self._dst = dst
         self._back = back
-        self._tr = src.crs.transformer_to_crs(dst.crs)
+        self._tr = src.crs.transformer_to_crs(dst.crs, force_over=True)
         self._clamps: Optional[Tuple[Tuple[float, float], Tuple[float, float]]] = None
         if src.crs.geographic:
             self._clamps = ((-180, 180), (-90, 90))
diff --git a/tests/test_geom.py b/tests/test_geom.py
index 7ccea762..565e2ea2 100644
--- a/tests/test_geom.py
+++ b/tests/test_geom.py
@@ -522,6 +522,53 @@ def test_gen_test_image_xy():
     assert isinstance(A, Affine)
 
 
+def test_geobox_overlap():
+    from odc.geo.types import xy_
+    from odc.geo.overlap import (
+        roi_boundary,
+        unstack_xy,
+        stack_xy,
+        gbox_boundary,
+        roi_from_points,
+        native_pix_transform,
+    )
+
+    pts_per_side = 5
+    padding = 1
+    align = True
+
+    dst_affine = Affine(
+        152.87405657034833,
+        0.0,
+        -20037508.342789244,
+        0.0,
+        -152.87405657034833,
+        -1995923.6825825237,
+    )
+    dst = GeoBox((256, 256), dst_affine, "EPSG:3857")
+
+    src_affine = Affine(10.0, 0.0, 99960.0, 0.0, -10.0, 8100040.0)
+    src = GeoBox((10980, 10980), src_affine, "EPSG:32701")
+
+    tr = native_pix_transform(src, dst)
+
+    xy = tr.back(unstack_xy(gbox_boundary(dst, pts_per_side)))
+    roi_src = roi_from_points(stack_xy(xy), src.shape, padding, align=align)
+
+    xy_pix_src = unstack_xy(roi_boundary(roi_src, pts_per_side))
+
+    xx, yy = np.asarray([pt.xy for pt in xy_pix_src]).T
+
+    # This goes via world transform to a pixel space
+    xys = tr([xy_(x, y) for x, y in zip(xx, yy)])
+
+    # Results should be within a resonable range in pixel space
+    # Not sure how to test it better.
+    for xy in xys:
+        assert xy.x >= 0 - 25.6
+        assert xy.y <= 256 + 25.6
+
+
 def test_fixed_point():
     aa = np.asarray([0, 0.5, 1])
     uu = to_fixed_point(aa, "uint8")