diff --git a/include/gsl/string_span b/include/gsl/string_span
index a1d2bb2..fc0dfeb 100644
--- a/include/gsl/string_span
+++ b/include/gsl/string_span
@@ -26,7 +26,7 @@
 #include <cstddef>   // for size_t, nullptr_t
 #include <cstdint>   // for PTRDIFF_MAX
 #include <cstring>
-#include <string>      // for basic_string, allocator, char_traits
+#include <string>    // for basic_string, allocator, char_traits
 #include <type_traits> // for declval, is_convertible, enable_if_t, add_...
 
 #if defined(_MSC_VER) && !defined(__clang__)