diff --git a/pyproject.toml b/pyproject.toml
index 8f6ac70..a7b47a0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "openscad_cpp_evaluator"
-version = "0.13.9"
+version = "0.13.10"
 description = "C++ OpenSCAD evaluator with Python bindings"
 readme = "README.md"
 requires-python = ">=3.12"
diff --git a/src/builtins/booleans.cpp b/src/builtins/booleans.cpp
index 534a246..e04bdec 100644
--- a/src/builtins/booleans.cpp
+++ b/src/builtins/booleans.cpp
@@ -176,7 +176,23 @@ std::vector<ColoredBody> generateCsg(Evaluator& ev, const CSGParams& params, con
 
         std::vector<ColoredBody> bodies3d, sections2d;
         for (const ColoredBody& c : split.foreground) {
-            if (c.body) bodies3d.push_back(c);
+            // A body whose own Manifold::Status() isn't NoError (e.g.
+            // NonFiniteVertex, from a degenerate accumulated transform deep
+            // in an unrelated ancestor's positioning math -- found via a
+            // real user script, snappy-reprap's z_tower_assembly chain,
+            // where one already-invalid sub-part silently zeroed out an
+            // entire 65-operand union of otherwise-valid geometry) must
+            // never reach Manifold's own `+`/`-`/`^` operators: unlike a
+            // genuinely empty operand (0 triangles, NoError), Manifold
+            // propagates a non-NoError status through boolean ops onto the
+            // WHOLE result instead of treating it as a no-op contributor,
+            // so a single bad part silently discards every valid sibling.
+            // Real OpenSCAD's CGAL backend doesn't hit this at all here
+            // (more robust to the same input) -- dropping the one invalid
+            // operand and unioning everything else is the closest match to
+            // its own behavior available without new numerical-robustness
+            // work on Manifold's own boolean ops.
+            if (c.body && c.body->Status() == manifold::Manifold::Error::NoError) bodies3d.push_back(c);
         }
         for (const ColoredBody& c : split.foreground) {
             if (c.section) sections2d.push_back(c);
diff --git a/tests/test_booleans.cpp b/tests/test_booleans.cpp
index bd10e54..2ff002a 100644
--- a/tests/test_booleans.cpp
+++ b/tests/test_booleans.cpp
@@ -87,6 +87,25 @@ TEST(Difference, EmptySubtractorLeavesBaseUnchanged) {
     EXPECT_NEAR(e.bodies[0].body->Volume(), 64.0, 1e-6);
 }
 
+TEST(Union, OneInvalidOperandDoesNotDiscardValidSiblings) {
+    // Regression: Manifold's own `+` propagates a non-NoError Status()
+    // (e.g. NonFiniteVertex, from a degenerate NaN-vertex polyhedron here --
+    // in the wild, from an accumulated transform deep in an unrelated
+    // ancestor's own positioning math) onto the WHOLE combined result
+    // instead of treating the bad operand as a no-op contributor. Before
+    // filtering invalid operands out in generateCsg, a single bad part
+    // anywhere in a many-operand union() silently discarded every valid
+    // sibling too -- found via a real user project (snappy-reprap) where
+    // this zeroed out an entire ~65-part extruder assembly with no warning.
+    Evaluated e = evalSrc("union() {"
+                          "  polyhedron(points=[[0,0,0],[2,0,0],[0,2,0],[0/0,0,2]],"
+                          "             faces=[[0,1,2],[0,3,1],[0,2,3],[1,3,2]]);"
+                          "  translate([10,0,0]) cube(2);"
+                          "}");
+    ASSERT_EQ(e.bodies.size(), 1u);
+    EXPECT_NEAR(e.bodies[0].body->Volume(), 8.0, 1e-6); // just the valid cube -- the NaN polyhedron is dropped, not fatal
+}
+
 // -- 2D-native boolean CSG (union/difference/intersection applied directly
 // to 2D children, not mediated through linear_extrude()) -----------------