diff --git a/libbuild2-autoconf/build/root.build b/libbuild2-autoconf/build/root.build
index 00c8dca..cb0e129 100644
--- a/libbuild2-autoconf/build/root.build
+++ b/libbuild2-autoconf/build/root.build
@@ -14,3 +14,5 @@ if ($cxx.class == 'msvc')
   cc.coptions += /wd4251 /wd4275 /wd4800
 elif ($cxx.id == 'gcc')
   cxx.coptions += -Wno-maybe-uninitialized -Wno-free-nonheap-object # libbutl
+elif ($cxx.id.type == 'clang' && $cxx.version.major >= 15)
+  cxx.coptions += -Wno-unqualified-std-cast-call