diff --git a/include/trajopt/constraint/differential/DifferentialConstraint.h b/include/trajopt/constraint/differential/DifferentialConstraint.h
index 189beac8..efbd9f95 100644
--- a/include/trajopt/constraint/differential/DifferentialConstraint.h
+++ b/include/trajopt/constraint/differential/DifferentialConstraint.h
@@ -6,13 +6,13 @@
 #include "trajopt/constraint/Constraint.h"
 #include "trajopt/constraint/differential/DifferentialCentripetalAccelerationConstraint.h"
 #include "trajopt/constraint/differential/DifferentialTangentialVelocityConstraint.h"
-#include "trajopt/util/AppendVariant.h"
+#include "trajopt/util/VariantCat.h"
 
 namespace trajopt {
 
 using DifferentialConstraint =
-    decltype(_append_variant(Constraint{}, AngularVelocityConstraint{},
-                             DifferentialTangentialVelocityConstraint{},
-                             DifferentialCentripetalAccelerationConstraint{}));
+    variant_cat_t<Constraint, AngularVelocityConstraint,
+                  DifferentialTangentialVelocityConstraint,
+                  DifferentialCentripetalAccelerationConstraint>;
 
 }  // namespace trajopt
diff --git a/include/trajopt/constraint/holonomic/HolonomicConstraint.h b/include/trajopt/constraint/holonomic/HolonomicConstraint.h
index 358c632b..3fc1263a 100644
--- a/include/trajopt/constraint/holonomic/HolonomicConstraint.h
+++ b/include/trajopt/constraint/holonomic/HolonomicConstraint.h
@@ -6,12 +6,12 @@
 #include "trajopt/constraint/Constraint.h"
 #include "trajopt/constraint/PointAtConstraint.h"
 #include "trajopt/constraint/holonomic/HolonomicVelocityConstraint.h"
-#include "trajopt/util/AppendVariant.h"
+#include "trajopt/util/VariantCat.h"
 
 namespace trajopt {
 
-using HolonomicConstraint = decltype(_append_variant(
-    Constraint{}, AngularVelocityConstraint{}, HolonomicVelocityConstraint{},
-    PointAtConstraint{}));
+using HolonomicConstraint =
+    variant_cat_t<Constraint, AngularVelocityConstraint,
+                  HolonomicVelocityConstraint, PointAtConstraint>;
 
 }  // namespace trajopt
diff --git a/include/trajopt/util/AppendVariant.h b/include/trajopt/util/AppendVariant.h
deleted file mode 100644
index b15dc8d5..00000000
--- a/include/trajopt/util/AppendVariant.h
+++ /dev/null
@@ -1,36 +0,0 @@
-// Copyright (c) TrajoptLib contributors
-
-#pragma once
-
-#include <variant>
-
-/**
- * @brief Generates a derived variant type including the types of a
- * base variant and additional types listed. This function should not
- * be evaluated. It may be used along with `decltype()`. For example:
- *
- * ```cpp
- * std::variant<int> myvar; // int
- * decltype(_append_variant(myvar, double())) myvar2; // int, double
- * myvar2 = 1;
- * myvar2 = 2.0;
- * ```
- *
- * @tparam Vs The types of the base variant.
- * @tparam Aps The types to append to the new variant type.
- * @param myvar A variant of the base typ, used only for type deduction.
- * @param newvals values of the new variant
- * @return a default-constructed variant of the derived type.
- */
-template <typename... Vs, typename... Aps>
-std::variant<Vs..., Aps...> _append_variant(
-    [[maybe_unused]] std::variant<Vs...> myvar,
-    [[maybe_unused]] Aps... newvals) {
-  return std::variant<Vs..., Aps...>();
-}
-
-template <typename... Vs, typename... Aps>
-inline std::variant<Vs...> _get_as_sub_vari(std::variant<Vs..., Aps...> myvar) {
-  std::get<1>(myvar);
-  return std::variant<Vs..., Aps...>();
-}
diff --git a/include/trajopt/util/VariantCat.h b/include/trajopt/util/VariantCat.h
new file mode 100644
index 00000000..f289e47a
--- /dev/null
+++ b/include/trajopt/util/VariantCat.h
@@ -0,0 +1,32 @@
+// Copyright (c) TrajoptLib contributors
+
+#pragma once
+
+#include <variant>
+
+namespace trajopt {
+
+namespace detail {
+
+//! @cond Doxygen_Suppress
+
+template <typename Variant, typename... Args>
+struct variant_cat;
+
+template <typename... Args0, typename... Args1>
+struct variant_cat<std::variant<Args0...>, Args1...> {
+  using type = std::variant<Args0..., Args1...>;
+};
+
+//! @endcond
+
+}  // namespace detail
+
+/**
+ * Defines a new variant type that appends the types Args... to the variant type
+ * Variant.
+ */
+template <typename Variant, typename... Args>
+using variant_cat_t = typename detail::variant_cat<Variant, Args...>::type;
+
+}  // namespace trajopt