diff --git a/cpp2rust/converter/converter.cpp b/cpp2rust/converter/converter.cpp
index 8cb26e93..a4c0ef1f 100644
--- a/cpp2rust/converter/converter.cpp
+++ b/cpp2rust/converter/converter.cpp
@@ -891,6 +891,11 @@ bool Converter::VisitCXXRecordDecl(clang::CXXRecordDecl *decl) {
       }
     }
 
+    EmitRustStructOrUnion(decl);
+  } else if (decl->isUnion()) {
+    if (!record_decls_.MarkDefined(GetRecordName(decl))) {
+      return false;
+    }
     EmitRustStructOrUnion(decl);
   } else {
     // FIXME: improve error handling
diff --git a/tests/unit/out/refcount/union_basic.rs b/tests/unit/out/refcount/union_basic.rs
index 0a509632..a9bd9e73 100644
--- a/tests/unit/out/refcount/union_basic.rs
+++ b/tests/unit/out/refcount/union_basic.rs
@@ -48,10 +48,10 @@ pub fn main() {
     std::process::exit(main_0());
 }
 fn main_0() -> i32 {
-    let u: Value<basic> = <Value<basic>>::default();
+    let u: Value<basic> = Rc::new(RefCell::new(<basic>::default()));
     (*u.borrow_mut()).i().write(42);
-    assert!((((((*u.borrow()).i().read()) == 42) as i32) != 0));
+    assert!((((*u.borrow()).i().read()) == 42));
     (*u.borrow_mut()).f().write(3.140000105E+0);
-    assert!((((((*u.borrow()).f().read()) == 3.140000105E+0) as i32) != 0));
+    assert!((((*u.borrow()).f().read()) == 3.140000105E+0));
     return 0;
 }
diff --git a/tests/unit/out/unsafe/union_basic.rs b/tests/unit/out/unsafe/union_basic.rs
index 43a45ff6..81e82df3 100644
--- a/tests/unit/out/unsafe/union_basic.rs
+++ b/tests/unit/out/unsafe/union_basic.rs
@@ -25,8 +25,8 @@ pub fn main() {
 unsafe fn main_0() -> i32 {
     let mut u: basic = <basic>::default();
     u.i = 42;
-    assert!(((((u.i) == (42)) as i32) != 0));
+    assert!(((u.i) == (42)));
     u.f = 3.140000105E+0;
-    assert!(((((u.f) == (3.140000105E+0)) as i32) != 0));
+    assert!(((u.f) == (3.140000105E+0)));
     return 0;
 }
diff --git a/tests/unit/union_basic.c b/tests/unit/union_basic.cpp
similarity index 100%
rename from tests/unit/union_basic.c
rename to tests/unit/union_basic.cpp