diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index 9227daf6365..8e9c64fc5b0 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -1024,7 +1024,11 @@
 #endif
 
 #ifndef Q_DECL_EQ_DELETE_X
-#  if defined(__cpp_deleted_function) && __cpp_deleted_function >= 202403L
+// Clang advertises the feature-testing macro but issues a warning
+// if one isn't also using C++26,
+// https://github.com/llvm/llvm-project/issues/109311
+#  if defined(__cpp_deleted_function) && __cpp_deleted_function >= 202403L \
+    && (!defined(Q_CC_CLANG_ONLY) || __cplusplus > 202302L) // C++26
 #    define Q_DECL_EQ_DELETE_X(reason) = delete(reason)
 #  else
 #    define Q_DECL_EQ_DELETE_X(reason) = delete