diff --git a/src/csg/tests/levelset/boolean.t.cpp b/src/csg/tests/levelset/boolean.t.cpp
index 826ecf1037cc27a22548eae4217bfc67b3148002..71486d5145ca860e7cb2bca396f8ec93148d0b35 100644
--- a/src/csg/tests/levelset/boolean.t.cpp
+++ b/src/csg/tests/levelset/boolean.t.cpp
@@ -27,10 +27,10 @@ TEST_CASE("Union3D", "[Levelset Boolean]") {
   CHECK(Approx(8 * 8 - 7.5 * 7.5) == my_levelset(0, 0, -7.5));
 
   CHECK_FALSE(0 < my_levelset(0, -9, 0));
-  CHECK_FALSE(Approx(-1) == my_levelset(0, -9, 0));
+  CHECK(Approx(-3) == my_levelset(0, -9, 0));
 
   CHECK_FALSE(0 < my_levelset(9, 0, 0));
-  CHECK_FALSE(Approx(-1) == my_levelset(9, 0, 0));
+  CHECK(Approx(-3) == my_levelset(9, 0, 0));
 }
 
 TEST_CASE("Intersection3D", "[Levelset Boolean]") {