diff --git a/tests/RefinementTest.cpp b/tests/RefinementTest.cpp
index ace1d7659..926aa3254 100644
--- a/tests/RefinementTest.cpp
+++ b/tests/RefinementTest.cpp
@@ -305,9 +305,11 @@ TEST_CASE("RefinementRestraints_gradient", "[Refinement]") {
 #ifdef JFJOCH_USE_CUDA
     if (get_gpu_count() > 0) {
         // the GPU's float evaluation of the same set
-        std::vector<MergedReflection> merged = asu_reflections(cell, *st.find_spacegroup(), 3.0);
-        RefinementReflections refl = PrepareRefinementReflections(merged, cell, *st.find_spacegroup(), 3.0);
-        auto gpu = MakeRefinementEngineGPU(0, cell, *st.find_spacegroup(), 3.0, refl, st.models[0], 100.0, SIZE_MAX);
+        // (the engine is made for a cell wide enough for its gather; the restraints do not read the cell)
+        const gemmi::UnitCell wide_cell(40, 40, 40, 90, 90, 90);
+        std::vector<MergedReflection> merged = asu_reflections(wide_cell, *st.find_spacegroup(), 3.0);
+        RefinementReflections refl = PrepareRefinementReflections(merged, wide_cell, *st.find_spacegroup(), 3.0);
+        auto gpu = MakeRefinementEngineGPU(0, wide_cell, *st.find_spacegroup(), 3.0, refl, st.models[0], 100.0, SIZE_MAX);
         REQUIRE(gpu);
         gpu->SetRestraints(0, set);
         std::vector<std::array<double, 4>> ggpu;