diff --git a/include/gsl/string_span b/include/gsl/string_span
index 0bb98d2..6b4c839 100644
--- a/include/gsl/string_span
+++ b/include/gsl/string_span
@@ -698,7 +698,7 @@ bool operator>=(const T& one, gsl::basic_string_span<CharT, Extent> other) GSL_N
     return !(one < other);
 }
 #endif
-} // namespace GSL
+} // namespace gsl
 
 #undef GSL_NOEXCEPT