diff --git a/include/fmt/format.h b/include/fmt/format.h
index 1710cf03..82ddb407 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -339,12 +339,15 @@ inline auto get_data(Container& c) -> typename Container::value_type* {
 #if defined(_SECURE_SCL) && _SECURE_SCL
 // Make a checked iterator to avoid MSVC warnings.
 template <typename T> using checked_ptr = stdext::checked_array_iterator<T*>;
-template <typename T> auto make_checked(T* p, size_t size) -> checked_ptr<T> {
+template <typename T>
+constexpr auto make_checked(T* p, size_t size) -> checked_ptr<T> {
   return {p, size};
 }
 #else
 template <typename T> using checked_ptr = T*;
-template <typename T> inline auto make_checked(T* p, size_t) -> T* { return p; }
+template <typename T> constexpr auto make_checked(T* p, size_t) -> T* {
+  return p;
+}
 #endif
 
 // Attempts to reserve space for n extra characters in the output range.