diff --git a/include/outcome/basic_result.hpp b/include/outcome/basic_result.hpp
index 880c359b3a..216d9d10d7 100644
--- a/include/outcome/basic_result.hpp
+++ b/include/outcome/basic_result.hpp
@@ -440,7 +440,7 @@ SIGNATURE NOT RECOGNISED
 SIGNATURE NOT RECOGNISED
 */
   OUTCOME_TEMPLATE(class ErrorCondEnum)
-  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(ErrorCondEnum()))),  //
+  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(std::declval<ErrorCondEnum>()))),  //
                     OUTCOME_TPRED(predicate::template enable_error_condition_converting_constructor<ErrorCondEnum>))
   constexpr basic_result(ErrorCondEnum &&t, error_condition_converting_constructor_tag /*unused*/ = error_condition_converting_constructor_tag()) noexcept(
   noexcept(error_type(make_error_code(static_cast<ErrorCondEnum &&>(t)))))  // NOLINT
diff --git a/single-header/outcome-basic.hpp b/single-header/outcome-basic.hpp
index 2d7a63ee5e..417400c720 100644
--- a/single-header/outcome-basic.hpp
+++ b/single-header/outcome-basic.hpp
@@ -4711,7 +4711,7 @@ SIGNATURE NOT RECOGNISED
 SIGNATURE NOT RECOGNISED
 */
   OUTCOME_TEMPLATE(class ErrorCondEnum)
-  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(ErrorCondEnum()))), //
+  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(std::declval<ErrorCondEnum>()))), //
                     OUTCOME_TPRED(predicate::template enable_error_condition_converting_constructor<ErrorCondEnum>))
   constexpr basic_result(ErrorCondEnum &&t, error_condition_converting_constructor_tag /*unused*/ = error_condition_converting_constructor_tag()) noexcept(
   noexcept(error_type(make_error_code(static_cast<ErrorCondEnum &&>(t))))) // NOLINT
diff --git a/single-header/outcome-experimental.hpp b/single-header/outcome-experimental.hpp
index e04481b1e2..8198150bd4 100644
--- a/single-header/outcome-experimental.hpp
+++ b/single-header/outcome-experimental.hpp
@@ -4736,7 +4736,7 @@ SIGNATURE NOT RECOGNISED
 SIGNATURE NOT RECOGNISED
 */
   OUTCOME_TEMPLATE(class ErrorCondEnum)
-  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(ErrorCondEnum()))), //
+  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(std::declval<ErrorCondEnum>()))), //
                     OUTCOME_TPRED(predicate::template enable_error_condition_converting_constructor<ErrorCondEnum>))
   constexpr basic_result(ErrorCondEnum &&t, error_condition_converting_constructor_tag /*unused*/ = error_condition_converting_constructor_tag()) noexcept(
   noexcept(error_type(make_error_code(static_cast<ErrorCondEnum &&>(t))))) // NOLINT
diff --git a/single-header/outcome.hpp b/single-header/outcome.hpp
index e8b75b9701..fa6a928e4e 100644
--- a/single-header/outcome.hpp
+++ b/single-header/outcome.hpp
@@ -5648,7 +5648,7 @@ SIGNATURE NOT RECOGNISED
 SIGNATURE NOT RECOGNISED
 */
   OUTCOME_TEMPLATE(class ErrorCondEnum)
-  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(ErrorCondEnum()))), //
+  OUTCOME_TREQUIRES(OUTCOME_TEXPR(error_type(make_error_code(std::declval<ErrorCondEnum>()))), //
                     OUTCOME_TPRED(predicate::template enable_error_condition_converting_constructor<ErrorCondEnum>))
   constexpr basic_result(ErrorCondEnum &&t, error_condition_converting_constructor_tag /*unused*/ = error_condition_converting_constructor_tag()) noexcept(
   noexcept(error_type(make_error_code(static_cast<ErrorCondEnum &&>(t))))) // NOLINT