diff --git a/include/experimental/__p0009_bits/mdspan.hpp b/include/experimental/__p0009_bits/mdspan.hpp
index 0bac391c..2100492a 100644
--- a/include/experimental/__p0009_bits/mdspan.hpp
+++ b/include/experimental/__p0009_bits/mdspan.hpp
@@ -452,8 +452,8 @@ class mdspan
   )
   MDSPAN_FORCE_INLINE_FUNCTION constexpr bool __is_index_oor(SizeType index, index_type extent) const noexcept {
     // Check for negative indices
-    if constexpr(std::is_signed_v<SizeType>) {
-      if(index < 0) {
+    if constexpr (std::is_signed_v<index_type>) {
+      if (static_cast<index_type>(index) < 0) {
         return true;
       }
     }