diff --git a/.github/workflows/ci_tests.yml b/.github/workflows/ci_tests.yml
index fac4c01..e350afd 100644
--- a/.github/workflows/ci_tests.yml
+++ b/.github/workflows/ci_tests.yml
@@ -41,6 +41,8 @@ jobs:
             args: ""
           - description: "Dynamic default"
             args: "-DBUILD_SHARED_LIBS=on"
+          - description: "static C++17"
+            args: "-DCMAKE_CXX_STANDARD=17"
           - description: "static C++20"
             args: "-DCMAKE_CXX_STANDARD=20"
           - description: "static C++23"
diff --git a/CMakePresets.json b/CMakePresets.json
index 0b645f2..ede9472 100644
--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -7,7 +7,7 @@
       "generator": "Ninja",
       "binaryDir": "${sourceDir}/build/${presetName}",
       "cacheVariables": {
-        "CMAKE_CXX_STANDARD": "20"
+        "CMAKE_CXX_STANDARD": "17"
       }
     },
     {
diff --git a/include/beman/exemplar/identity.hpp b/include/beman/exemplar/identity.hpp
index 789c319..9463125 100644
--- a/include/beman/exemplar/identity.hpp
+++ b/include/beman/exemplar/identity.hpp
@@ -30,11 +30,7 @@ struct __is_transparent; // not defined
 struct identity {
     // Returns `t`.
     template <class T>
-#if defined(__cpp_constexpr)
-    constexpr
-#endif
-        T&&
-        operator()(T&& t) const noexcept {
+    constexpr T&& operator()(T&& t) const noexcept {
         return std::forward<T>(t);
     }