diff --git a/include/gauxc/molecule.hpp b/include/gauxc/molecule.hpp
index ebff857b..ce9aaa6a 100644
--- a/include/gauxc/molecule.hpp
+++ b/include/gauxc/molecule.hpp
@@ -16,10 +16,16 @@
 namespace GauXC {
 
 class Molecule : public std::vector<Atom> {
+private:
+  /// Tests if the base class can be constructed from @p Args
+  template <typename... Args>
+  static constexpr auto can_construct_base_v = 
+    std::is_constructible_v<std::vector<Atom>, Args...>;
 
 public:
 
-  template <typename... Args>
+  template <typename... Args, 
+            typename = std::enable_if_t<can_construct_base_v<Args...>>>
   Molecule( Args&&... args ) :
     std::vector<Atom>( std::forward<Args>(args)... ) { }
 
diff --git a/tests/ini_input.hpp b/tests/ini_input.hpp
index bd0de809..1577f2ee 100644
--- a/tests/ini_input.hpp
+++ b/tests/ini_input.hpp
@@ -24,7 +24,7 @@
  */
 static inline std::string& trim_left(std::string &s) {
     s.erase(s.begin(), std::find_if(s.begin(), s.end(),
-            std::not1(std::ptr_fun<int, int>(std::isspace))));
+            [](int ch) { return !std::isspace(ch); }));
     return s;
 }; // trim_left
 
@@ -36,7 +36,7 @@ static inline std::string& trim_left(std::string &s) {
  */
 static inline std::string& trim_right(std::string &s) {
     s.erase(std::find_if(s.rbegin(), s.rend(),
-            std::not1(std::ptr_fun<int, int>(std::isspace))).base(), s.end());
+            [](int ch) { return !std::isspace(ch); }).base(), s.end());
     return s;
 }; // trim_right
 
diff --git a/tests/moltypes_test.cxx b/tests/moltypes_test.cxx
index f63dce91..5ed00c55 100644
--- a/tests/moltypes_test.cxx
+++ b/tests/moltypes_test.cxx
@@ -47,6 +47,13 @@ TEST_CASE("Molecule", "[moltypes]") {
 
   size_t natoms_gen = 40;
 
+  SECTION("Default") {
+
+    Molecule mol;
+
+    CHECK(mol.natoms() == 0);
+  }
+
   SECTION("From std::vector<Atom>") {
 
     std::vector<Atom> atoms;
@@ -113,6 +120,25 @@ TEST_CASE("Molecule", "[moltypes]") {
 
   }
 
+  SECTION("Copy ctor") {
+
+    std::vector<Atom> atoms{Atom(AtomicNumber(1), 0.0, 0.0, 0.0)};
+    Molecule mol(atoms);
+
+    Molecule mol_copy(mol);
+    CHECK(mol == mol_copy);
+  }
+
+
+  SECTION("Move ctor") {
+
+    std::vector<Atom> atoms{Atom(AtomicNumber(1), 0.0, 0.0, 0.0)};
+    Molecule mol(atoms);
+
+    Molecule mol_copy(mol);
+    Molecule mol_move(std::move(mol));
+    CHECK(mol_move == mol_copy);
+  }
 
 }