diff --git a/include/gsl/span b/include/gsl/span
index c2e0135..2133baa 100644
--- a/include/gsl/span
+++ b/include/gsl/span
@@ -441,7 +441,7 @@ public:
 
     template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent == dynamic_extent, int> = 0>
     constexpr span(pointer firstElem, pointer lastElem) noexcept
-        : storage_(firstElem, gsl::narrow_cast<std::size_t>(lastElem - firstElem))
+        : storage_(firstElem, narrow_cast<std::size_t>(lastElem - firstElem))
     {}
 
     template <std::size_t N,