diff --git a/src/corelib/tools/qspan.h b/src/corelib/tools/qspan.h
index 65362f94b24..f6ec8280fbc 100644
--- a/src/corelib/tools/qspan.h
+++ b/src/corelib/tools/qspan.h
@@ -425,7 +425,7 @@ public:
     [[nodiscard]] constexpr QSpan<T> subspan(size_type pos, size_type n) const { return subspan(pos).first(n); }
 
     // Qt-compatibility API:
-    [[nodiscard]] bool isEmpty() const noexcept { return empty(); }
+    [[nodiscard]] constexpr bool isEmpty() const noexcept { return empty(); }
     // nullary first()/last() clash with first<>() and last<>(), so they're not provided for QSpan
     [[nodiscard]] constexpr QSpan<T> sliced(size_type pos) const { return subspan(pos); }
     [[nodiscard]] constexpr QSpan<T> sliced(size_type pos, size_type n) const { return subspan(pos, n); }