diff --git a/src/csg/parser.cpp b/src/csg/parser.cpp
index b3a43134aada44895404459a7cab0b7d0c3709fb..7e8491e5e74c531730c7c9086e43586853ab68b6 100644
--- a/src/csg/parser.cpp
+++ b/src/csg/parser.cpp
@@ -260,6 +260,7 @@ template <> struct action<attr_list> {
     std::stringstream ss(in.string());
     st.curr_attrs.push_back(st.curr_attr);
     st.curr_attr.clear();
+    st.current_name.clear();
   }
 };
 
@@ -510,6 +511,7 @@ template <> struct action<cylinder> {
       if (curr_attr.count("r1") || curr_attr.count("r2")) {
         std::cout << " ERROR: cannot specify both r and (r1 or r2); ambiguous "
                   << std::endl;
+        assert(false);
       }
       csg::Cylinder cyl;
       cyl.name = get_name(curr_attr);
@@ -640,7 +642,8 @@ template <> struct action<string_literal> {
     std::stringstream ss(in.string());
     std::string v;
     ss >> v;
-    st.curr_attr[st.current_name] = v;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = v;
   }
 };
 
@@ -650,7 +653,8 @@ template <> struct action<double_> {
     std::stringstream ss(in.string());
     double v;
     ss >> v;
-    st.curr_attr[st.current_name] = v;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = v;
   }
 };
 
@@ -658,7 +662,8 @@ template <> struct action<true_literal> {
   template <typename Input>
   static void apply(const Input &in, parser_state &st) {
     std::stringstream ss(in.string());
-    st.curr_attr[st.current_name] = true;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = true;
   }
 };
 
@@ -666,7 +671,8 @@ template <> struct action<false_literal> {
   template <typename Input>
   static void apply(const Input &in, parser_state &st) {
     std::stringstream ss(in.string());
-    st.curr_attr[st.current_name] = false;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = false;
   }
 };
 
@@ -674,7 +680,8 @@ template <> struct action<undef_literal> {
   template <typename Input>
   static void apply(const Input &in, parser_state &st) {
     std::stringstream ss(in.string());
-    st.curr_attr[st.current_name] = UNDEFINED_STR;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = UNDEFINED_STR;
   }
 };
 
@@ -682,7 +689,8 @@ template <> struct action<vector_attr> {
   template <typename Input>
   static void apply(const Input &in, parser_state &st) {
     std::stringstream ss(in.string());
-    st.curr_attr[st.current_name] = st.current_vec;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = st.current_vec;
     st.current_vec.clear();
   }
 };
@@ -691,7 +699,8 @@ template <> struct action<matrix_attr> {
   template <typename Input>
   static void apply(const Input &in, parser_state &st) {
     std::stringstream ss(in.string());
-    st.curr_attr[st.current_name] = st.current_matrix;
+    if (!st.current_name.empty())
+      st.curr_attr[st.current_name] = st.current_matrix;
     st.current_matrix.clear();
   }
 };
diff --git a/src/csg/tests/parser/boolean.t.cpp b/src/csg/tests/parser/boolean.t.cpp
index b96d85ce52df6aa2c865b8f4d4967600e8e379ea..6cb885bea85cff116d3ce0e3e6a2c7d02d0b8d5d 100644
--- a/src/csg/tests/parser/boolean.t.cpp
+++ b/src/csg/tests/parser/boolean.t.cpp
@@ -92,3 +92,12 @@ circle(size = [1,2], center=true);
 )");
   CHECK(st == nullptr);
 }
+
+TEST_CASE("sphere and cylinder union", "[csg]") {
+  auto st = csg::parse_csg(R"(
+sphere(r = 0.1);
+multmatrix([[1, 0, 0, 0.5], [0, 1, 0, 0.1], [0, 0, 1, 0], [0, 0, 0, 1]]) {
+   cylinder(h = 0.1, r1 = 0.1, r2 = 0.1, center = false);
+}
+)");
+}