diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index d98b91d4419..a9168af4acc 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -469,7 +469,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  return 1;
 	else if constexpr (__rank == 2)
 	  return __r == 0 ? 1 : __exts.extent(0);
-	else if constexpr (__all_dynamic(__sta_exts))
+	else if constexpr (__all_dynamic(std::span(__sta_exts).first(__rank-1)))
 	  return __extents_prod(__exts, 1, 0, __r);
 	else
 	  {
@@ -489,7 +489,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  return 1;
 	else if constexpr (__rank == 2)
 	  return __r == 0 ? __exts.extent(1) : 1;
-	else if constexpr (__all_dynamic(__sta_exts))
+	else if constexpr (__all_dynamic(std::span(__sta_exts).last(__rank-1)))
 	  return __extents_prod(__exts, 1, __r + 1, __rank);
 	else
 	  {