diff --git a/pytential/qbx/__init__.py b/pytential/qbx/__init__.py
index d3cd843a7e1a0b42ab49be23e02d3e6c35d302ef..b3bb102f66416aa34eb8f3867de4edd8a409ba66 100644
--- a/pytential/qbx/__init__.py
+++ b/pytential/qbx/__init__.py
@@ -106,6 +106,12 @@ class QBXLayerPotentialSource(LayerPotentialSourceBase):
 
         # {{{ argument processing
 
+        if fine_order is None:
+            raise ValueError("fine_order must be provided.")
+
+        if qbx_order is None:
+            raise ValueError("qbx_order must be provided.")
+
         if target_stick_out_factor is not _not_provided:
             from warnings import warn
             warn("target_stick_out_factor has been renamed to "
diff --git a/test/test_global_qbx.py b/test/test_global_qbx.py
index d0128819b8d01d3c3d6c33b84f7848f9b6a5a9a7..86832d6eb2fb33b7ada862a96e1f748d5f5da050 100644
--- a/test/test_global_qbx.py
+++ b/test/test_global_qbx.py
@@ -96,7 +96,9 @@ def run_source_refinement_test(ctx_getter, mesh, order, helmholtz_k=None):
 
     from pytential.qbx.utils import TreeCodeContainer
 
-    lpot_source = QBXLayerPotentialSource(discr, order)
+    lpot_source = QBXLayerPotentialSource(discr,
+            qbx_order=order,  # not used in refinement
+            fine_order=order)
     del discr
 
     expansion_disturbance_tolerance = 0.025
@@ -239,7 +241,9 @@ def test_target_association(ctx_getter, curve_name, curve_f, nelements,
 
     discr = Discretization(cl_ctx, mesh, factory)
 
-    lpot_source, conn = QBXLayerPotentialSource(discr, order).with_refinement()
+    lpot_source, conn = QBXLayerPotentialSource(discr,
+            qbx_order=order,  # not used in target association
+            fine_order=order).with_refinement()
     del discr
 
     from pytential.qbx.utils import get_interleaved_centers
@@ -417,7 +421,9 @@ def test_target_association_failure(ctx_getter):
             InterpolatoryQuadratureSimplexGroupFactory
     factory = InterpolatoryQuadratureSimplexGroupFactory(order)
     discr = Discretization(cl_ctx, mesh, factory)
-    lpot_source = QBXLayerPotentialSource(discr, order)
+    lpot_source = QBXLayerPotentialSource(discr,
+            qbx_order=order,  # not used in target association
+            fine_order=order)
 
     # }}}