diff --git a/DRAFT.md b/DRAFT.md
index 419ef92d..fb5254ef 100644
--- a/DRAFT.md
+++ b/DRAFT.md
@@ -459,13 +459,13 @@ class indirect {
 
   constexpr indirect();
 
-  constexpr indirect(allocator_arg_t, const Allocator& alloc);
+  explicit constexpr indirect(allocator_arg_t, const Allocator& alloc);
 
   template <class U, class... Us>
   explicit constexpr indirect(U&& u, Us&&... us);
 
   template <class U, class... Us>
-  constexpr indirect(allocator_arg_t, const Allocator& alloc,
+  explicit constexpr indirect(allocator_arg_t, const Allocator& alloc,
                      U&& u, Us&&... us);
 
   constexpr indirect(const indirect& other);
@@ -601,7 +601,7 @@ indirect(std::allocator_arg_t, Alloc, Value) -> indirect<
 #### X.Y.3 Constructors [indirect.ctor]
 
 ```c++
-constexpr indirect()
+explicit constexpr indirect()
 ```
 
 1. _Mandates_: `is_default_constructible_v<T>` is true.
@@ -612,7 +612,7 @@ constexpr indirect()
 3. _Postconditions_: `*this` is not valueless.
 
 ```c++
-constexpr indirect(allocator_arg_t, const Allocator& alloc);
+explicit constexpr indirect(allocator_arg_t, const Allocator& alloc);
 ```
 
 4. _Mandates_: `is_default_constructible_v<T>` is `true`.
@@ -630,7 +630,7 @@ explicit constexpr indirect(U&& u, Us&&... us);
 
 ```c++
 template <class U, class... Us>
-constexpr indirect(allocator_arg_t, const Allocator& alloc, U&& u, Us&& ...us);
+explicit constexpr indirect(allocator_arg_t, const Allocator& alloc, U&& u, Us&& ...us);
 ```
 
 8. _Constraints_: `is_constructible_v<T, U, Us...>` is `true`.
@@ -1064,13 +1064,15 @@ class polymorphic {
   using pointer = typename allocator_traits<Allocator>::pointer;
   using const_pointer  = typename allocator_traits<Allocator>::const_pointer;
 
-  constexpr polymorphic();
+  explicit constexpr polymorphic();
+
+  explicit constexpr polymorphic(allocator_arg_t, const Allocator& alloc);
 
   template <class U, class... Ts>
   explicit constexpr polymorphic(in_place_type_t<U>, Ts&&... ts);
 
   template <class U, class... Ts>
-  constexpr polymorphic(allocator_arg_t, const Allocator& alloc,
+  explicit constexpr polymorphic(allocator_arg_t, const Allocator& alloc,
                         in_place_type_t<U>, Ts&&... ts);
 
   constexpr polymorphic(const polymorphic& other);
@@ -1111,7 +1113,7 @@ class polymorphic {
 #### X.Z.3 Constructors [polymorphic.ctor]
 
 ```c++
-constexpr polymorphic()
+explicit constexpr polymorphic()
 ```
 
 1. _Mandates_: `is_default_constructible_v<T>` is `true`,
@@ -1123,7 +1125,7 @@ constexpr polymorphic()
 3. _Postconditions_: `*this` is not valueless.
 
 ```c++
-constexpr polymorphic(allocator_arg_t, const Allocator& alloc);
+explicit constexpr polymorphic(allocator_arg_t, const Allocator& alloc);
 ```
 
 4. _Mandates_: `is_default_constructible_v<T>` is `true`,
@@ -1143,7 +1145,7 @@ explicit constexpr polymorphic(in_place_type_t<U>, Ts&&... ts);
 
 ```c++
 template <class U, class... Ts>
-constexpr polymorphic(allocator_arg_t, const Allocator& alloc,
+explicit constexpr polymorphic(allocator_arg_t, const Allocator& alloc,
                       in_place_type_t<U>, Ts&&... ts);
 ```
 
diff --git a/indirect.h b/indirect.h
index d36c3816..6fd0181c 100644
--- a/indirect.h
+++ b/indirect.h
@@ -66,14 +66,15 @@ class indirect {
   using pointer = typename allocator_traits::pointer;
   using const_pointer = typename allocator_traits::const_pointer;
 
-  constexpr indirect()
+  explicit constexpr indirect()
     requires std::is_default_constructible_v<A>
   {
     static_assert(std::is_default_constructible_v<T>);
     p_ = construct_from(alloc_);
   }
 
-  constexpr indirect(std::allocator_arg_t, const A& alloc) : alloc_(alloc) {
+  explicit constexpr indirect(std::allocator_arg_t, const A& alloc)
+      : alloc_(alloc) {
     static_assert(std::is_default_constructible_v<T>);
     p_ = construct_from(alloc_);
   }
@@ -89,7 +90,8 @@ class indirect {
   }
 
   template <class U, class... Us>
-  constexpr indirect(std::allocator_arg_t, const A& alloc, U&& u, Us&&... us)
+  explicit constexpr indirect(std::allocator_arg_t, const A& alloc, U&& u,
+                              Us&&... us)
     requires(std::constructible_from<T, U &&, Us && ...> &&
              !std::is_same_v<std::remove_cvref_t<U>, indirect>)
       : alloc_(alloc) {
diff --git a/polymorphic.h b/polymorphic.h
index 7bd88385..cabf9a83 100644
--- a/polymorphic.h
+++ b/polymorphic.h
@@ -112,7 +112,7 @@ class polymorphic {
   using pointer = typename allocator_traits::pointer;
   using const_pointer = typename allocator_traits::const_pointer;
 
-  constexpr polymorphic() {
+  explicit constexpr polymorphic() {
     static_assert(std::is_default_constructible_v<T>);
     using cb_allocator = typename std::allocator_traits<
         A>::template rebind_alloc<detail::direct_control_block<T, T, A>>;
@@ -128,7 +128,8 @@ class polymorphic {
     }
   }
 
-  constexpr polymorphic(std::allocator_arg_t, const A& alloc) : alloc_(alloc) {
+  explicit constexpr polymorphic(std::allocator_arg_t, const A& alloc)
+      : alloc_(alloc) {
     static_assert(std::is_default_constructible_v<T>);
     using cb_allocator = typename std::allocator_traits<
         A>::template rebind_alloc<detail::direct_control_block<T, T, A>>;
@@ -164,8 +165,8 @@ class polymorphic {
   }
 
   template <class U, class... Ts>
-  constexpr polymorphic(std::allocator_arg_t, const A& alloc,
-                        std::in_place_type_t<U>, Ts&&... ts)
+  explicit constexpr polymorphic(std::allocator_arg_t, const A& alloc,
+                                 std::in_place_type_t<U>, Ts&&... ts)
     requires std::constructible_from<U, Ts&&...> &&
              std::copy_constructible<U> &&
              (std::derived_from<U, T> || std::same_as<U, T>)