diff --git a/include/fmt/core.h b/include/fmt/core.h
index 19cb05b5..f88b4cfe 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -396,7 +396,7 @@ template <typename Char> class basic_string_view {
   FMT_CONSTEXPR
 #endif
   FMT_INLINE basic_string_view(const Char* s) : data_(s) {
-    if (std::is_same<Char, char>::value)
+    if (std::is_same<Char, char>::value && !detail::is_constant_evaluated())
       size_ = std::strlen(reinterpret_cast<const char*>(s));
     else
       size_ = std::char_traits<Char>::length(s);