diff --git a/expected.hpp b/expected.hpp
index 73f9f16..874f467 100644
--- a/expected.hpp
+++ b/expected.hpp
@@ -606,28 +606,28 @@ namespace util
     constexpr const T& value() const&
     {
       if (!has_value())
-        throw std::logic_error();
+        throw std::logic_error("precondition error: doesn't have value");
       return **this;
     }
 
     constexpr T& value() &
     {
       if (!has_value())
-        throw std::logic_error();
+        throw std::logic_error("precondition error: doesn't have value");
       return **this;
     }
 
     constexpr const T&& value() const&&
     {
       if (!has_value())
-        throw std::logic_error();
+        throw std::logic_error("precondition error: doesn't have value");
       return *std::move(*this);
     }
 
     constexpr T&& value() &&
     {
       if (!has_value())
-        throw std::logic_error();
+        throw std::logic_error("precondition error: doesn't have value");
       return *std::move(*this);
     }
 
@@ -658,7 +658,7 @@ namespace util
     template <typename U>
     constexpr T value_or(U&& v) const&
     {
-      if (has_value)
+      if (has_value())
         return **this;
       else
         return static_cast<T>(std::forward<U>(v));
@@ -667,7 +667,7 @@ namespace util
     template <typename U>
     constexpr T value_or(U&& v) &&
     {
-      if (has_value)
+      if (has_value())
         return std::move(**this);
       else
         return static_cast<T>(std::forward<U>(v));
@@ -930,7 +930,7 @@ namespace util
     constexpr void value() const
     {
       if (!has_value())
-        throw std::logic_error();
+        throw std::logic_error("precondition error: doesn't have value");
     }
 
     constexpr const E& error() const&
diff --git a/monads.hpp b/monads.hpp
index 928f401..fd62580 100644
--- a/monads.hpp
+++ b/monads.hpp
@@ -67,7 +67,7 @@ namespace monad
   }
 
   template <typename T, typename... Ts>
-  constexpr std::error_code get_error(T&& v, Ts&&... vs) noexcept
+  std::error_code get_error(T&& v, Ts&&... vs) noexcept
   {
     if constexpr (is_monad_v<std::decay_t<T>>)
       if (!has_value(v))