diff --git a/src/aether-miscpp/meta/function_signature.h b/src/aether-miscpp/meta/function_signature.h
index a27bf59..655f865 100644
--- a/src/aether-miscpp/meta/function_signature.h
+++ b/src/aether-miscpp/meta/function_signature.h
@@ -22,8 +22,11 @@
 #include "aether-miscpp/meta/type_list.h"
 
 namespace ae {
+template <typename Signature>
+struct FunctionSignatureTraits;
+
 template <typename Ret, typename... Args>
-struct FunctionSignatureImpl {
+struct FunctionSignatureTraits<Ret(Args...)> {
   using ret = Ret;
   using args = TypeList<Args...>;
   using signature = ret(args, ...);
@@ -31,15 +34,16 @@ struct FunctionSignatureImpl {
 };
 
 template <typename R, typename... Args>
-auto GetFunctionSignature(R (*)(Args...)) -> FunctionSignatureImpl<R, Args...>;
+auto GetFunctionSignature(R (*)(Args...))
+    -> FunctionSignatureTraits<R(Args...)>;
 
 template <typename R, typename C, typename... Args>
 auto GetFunctionSignature(R (C::*)(Args...))
-    -> FunctionSignatureImpl<R, Args...>;
+    -> FunctionSignatureTraits<R(Args...)>;
 
 template <typename R, typename C, typename... Args>
 auto GetFunctionSignature(R (C::*)(Args...) const)
-    -> FunctionSignatureImpl<R, Args...>;
+    -> FunctionSignatureTraits<R(Args...)>;
 
 template <typename Callable>
 auto GetFunctionSignature(Callable)
diff --git a/src/aether-miscpp/types/small_function.h b/src/aether-miscpp/types/small_function.h
index 63b6742..aa14b07 100644
--- a/src/aether-miscpp/types/small_function.h
+++ b/src/aether-miscpp/types/small_function.h
@@ -105,9 +105,6 @@ template <typename TCallable, typename TSource, typename TRet,
  * conversion.
  */
 concept CompatibleCallable =
-    std::constructible_from<TCallable, TSource> &&
-    std::is_nothrow_constructible_v<TCallable, TSource> &&
-    std::is_nothrow_move_constructible_v<TCallable> &&
     std::invocable<TCallable&, TArgs&&...> &&
     (std::is_void_v<TRet> ||
      std::is_convertible_v<std::invoke_result_t<TCallable&, TArgs&&...>, TRet>);
@@ -154,6 +151,11 @@ class SmallFunction<TRet(TArgs...), Size, Alignment> {
                   "SmallFunction target size exceeds storage size");
     static_assert(alignof(Type) <= Alignment,
                   "SmallFunction target alignment exceeds storage alignment");
+    static_assert(std::constructible_from<Type, TFunctor> &&
+                      std::is_nothrow_constructible_v<Type, TFunctor> &&
+                      std::is_nothrow_move_constructible_v<Type>,
+                  "TFunctor must meet specific construction constraints");
+
     new (storage_.data()) Type{std::forward<TFunctor>(functor)};
   }
 
@@ -175,6 +177,12 @@ class SmallFunction<TRet(TArgs...), Size, Alignment> {
     static_assert(
         alignof(Type) <= Alignment,
         "SmallFunction MethodPtr target alignment exceeds storage alignment");
+
+    static_assert(std::constructible_from<Type, MPtr> &&
+                      std::is_nothrow_constructible_v<Type, MPtr> &&
+                      std::is_nothrow_move_constructible_v<Type>,
+                  "MPtr must meet specific construction constraints");
+
     new (storage_.data()) Type{std::forward<MPtr>(method_ptr)};
   }