diff --git a/autolens/point/solver/shape_solver.py b/autolens/point/solver/shape_solver.py
index 1f35b01cb..e5ac6b650 100644
--- a/autolens/point/solver/shape_solver.py
+++ b/autolens/point/solver/shape_solver.py
@@ -21,6 +21,7 @@
 
 import autoarray as aa
 
+from autoarray.structures.triangles.array import MAX_CONTAINING_SIZE
 from autoarray.structures.triangles.shape import Shape
 
 import autogalaxy as ag
@@ -582,8 +583,9 @@ class ShapeSolver(AbstractSolver):
     ---
     ``ShapeSolver`` is a NumPy-only solver and rejects ``use_jax=True`` / ``xp=jax.numpy``.
     The JAX triangle containers keep static shapes by truncating every refinement step to
-    ``ArrayTriangles.MAX_CONTAINING_SIZE`` (15) triangles — ample for a ``Point``, which
-    lies inside a handful of triangles, and meaningless for a shape with area, whose kept
+    ``autoarray.structures.triangles.array.MAX_CONTAINING_SIZE`` triangles (the cap the
+    `NotImplementedError` message quotes) — ample for a ``Point``, which lies inside a
+    handful of triangles, and meaningless for a shape with area, whose kept
     set grows with the size of its images. Before this was found, ``use_jax=True`` was
     silently ignored (``find_magnification`` hardcoded ``xp=np``); routing it through
     ``self._xp`` instead would have replaced a silently-ignored flag with a silently wrong
@@ -594,10 +596,11 @@ class ShapeSolver(AbstractSolver):
 
     # The one message both rejection routes raise, so a caller sees the same explanation
     # whether they set `use_jax=True` or passed `xp=jax.numpy` -- and, since it is a plain
-    # string, whether or not JAX is installed.
+    # string, whether or not JAX is installed. The cap is read from the (NumPy-only)
+    # `autoarray.structures.triangles.array` module, so the number cannot drift from it.
     _JAX_REJECTED_MESSAGE = (
         "ShapeSolver does not support JAX. The JAX triangle containers truncate "
-        "every refinement step to ArrayTriangles.MAX_CONTAINING_SIZE (15) "
+        f"every refinement step to MAX_CONTAINING_SIZE ({MAX_CONTAINING_SIZE}) "
         "triangles to keep static shapes, which is enough for a Point but not for "
         "a Shape with area: the kept triangles of an extended source number in the "
         "thousands, so the JAX path silently measures a small fraction of the "
diff --git a/test_autolens/point/triangles/test_shape_solver.py b/test_autolens/point/triangles/test_shape_solver.py
index e90887568..0739bf4b6 100644
--- a/test_autolens/point/triangles/test_shape_solver.py
+++ b/test_autolens/point/triangles/test_shape_solver.py
@@ -20,6 +20,7 @@
 import autoarray as aa
 import autolens as al
 
+from autoarray.structures.triangles.array import MAX_CONTAINING_SIZE
 from autoarray.structures.triangles.shape import Circle, Polygon, Square, Triangle
 from autolens.point.solver.shape_solver import ShapeSolver
 
@@ -575,7 +576,7 @@ def test_use_jax_solver_is_rejected_rather_than_silently_wrong(image_grid, sis_t
         with pytest.raises(NotImplementedError) as exc_info:
             call()
 
-        assert "MAX_CONTAINING_SIZE" in str(exc_info.value)
+        assert f"MAX_CONTAINING_SIZE ({MAX_CONTAINING_SIZE})" in str(exc_info.value)
 
 
 def test_explicit_jax_module_is_rejected_rather_than_silently_wrong(
@@ -598,17 +599,18 @@ def test_explicit_jax_module_is_rejected_rather_than_silently_wrong(
             tracer=sis_tracer, shape=Circle(0.3, 0.0, radius=0.1), xp=jnp
         )
 
-    assert "MAX_CONTAINING_SIZE" in str(exc_info.value)
+    assert f"MAX_CONTAINING_SIZE ({MAX_CONTAINING_SIZE})" in str(exc_info.value)
 
 
 @pytest.mark.xfail(
     strict=True,
     reason=(
         "DEFERRED: the JAX triangle containers truncate every refinement step to "
-        "ArrayTriangles.MAX_CONTAINING_SIZE (15) triangles to keep static shapes. That is "
-        "enough for a Point but not for a Shape with area, so the JAX path keeps 15 of the "
-        "~800 triangles the NumPy path keeps and measures a magnification of 0.13 where "
-        "the truth is 6.86. Lifting the cap is a redesign of the JAX containers (the cap "
+        f"MAX_CONTAINING_SIZE ({MAX_CONTAINING_SIZE}) triangles to keep static shapes. That "
+        "is enough for a Point but not for a Shape with area, so the JAX path keeps "
+        f"{MAX_CONTAINING_SIZE} of the "
+        "~800 triangles the NumPy path keeps and measures a magnification orders of "
+        "magnitude too small (0.13 at the original cap of 15, where the truth is 6.86). Lifting the cap is a redesign of the JAX containers (the cap "
         "is what makes their shapes static, and an extended source has no static bound), "
         "not a fix in ShapeSolver, so it is deferred and ShapeSolver raises on use_jax "
         "instead. Remove this xfail when the containers grow a dynamic kept set."