diff --git a/tests/ModelScaleGPUTest.cpp b/tests/ModelScaleGPUTest.cpp
index 3728c81b9..8dbd576f8 100644
--- a/tests/ModelScaleGPUTest.cpp
+++ b/tests/ModelScaleGPUTest.cpp
@@ -212,8 +212,12 @@ void CheckSameScale(const ModelScaleParams &gpu, const gemmi::Scaling<float> &cp
     const double b_cpu[6] = {cpu.b_star.u11, cpu.b_star.u22, cpu.b_star.u33,
                              cpu.b_star.u12, cpu.b_star.u13, cpu.b_star.u23};
     CHECK(std::fabs(gpu.k_overall - cpu.k_overall) <= 1e-4 * std::fabs(cpu.k_overall));
+    // b_star = F B_cart F^T, so a B of 0.001 A^2 is 0.001 / a^2 in it for the longest edge a. Without that
+    // floor a fit whose B comes out near zero is held to 1e-4 of almost nothing (a cubic case at B 0.6 A^2
+    // differed by 1e-4 A^2).
+    const double edge = std::max({cpu.cell.a, cpu.cell.b, cpu.cell.c});
     for (int i = 0; i < 6; i++)
-        CHECK(std::fabs(gpu.b_star[i] - b_cpu[i]) <= 1e-4 * MaxAbs(b_cpu) + 1e-12);
+        CHECK(std::fabs(gpu.b_star[i] - b_cpu[i]) <= 1e-4 * MaxAbs(b_cpu) + 1e-3 / (edge * edge));
 }
 
 struct Case {
diff --git a/tests/WriteReflectionsTest.cpp b/tests/WriteReflectionsTest.cpp
index 83ed12ab7..7f3e070ab 100644
--- a/tests/WriteReflectionsTest.cpp
+++ b/tests/WriteReflectionsTest.cpp
@@ -200,10 +200,13 @@ TEST_CASE("SHELX .hkl of unmerged fulls: fixed 3I4,2F8.2, scaled to fit, 0 0 0 t
     const auto path = (std::filesystem::temp_directory_path() / "jfjoch_scaled_fulls_test.hkl").string();
     WriteShelxHklReflections(fulls, path, 2);
 
-    std::ifstream in(path);
     std::vector<std::string> lines;
-    for (std::string line; std::getline(in, line);)
-        lines.push_back(line);
+    {
+        // Closed before the remove: Windows refuses to delete a file that is still open.
+        std::ifstream in(path);
+        for (std::string line; std::getline(in, line);)
+            lines.push_back(line);
+    }
     std::filesystem::remove(path);
 
     REQUIRE(lines.size() == 4);