diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 098cda44db22..d9541d13d9eb 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -11,7 +11,9 @@ config UML
 	select ARCH_HAS_CACHE_LINE_SIZE
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_FORTIFY_SOURCE
-	select ARCH_HAS_GCOV_PROFILE_ALL
+	# Clang 20 & 21 miscompute __builtin_object_size() under -fprofile-arcs
+	# on 32-bit, causing spurious compile-time errors in check_copy_size().
+	select ARCH_HAS_GCOV_PROFILE_ALL if !(!64BIT && CLANG_VERSION >= 200000 && CLANG_VERSION < 220100)
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_STRNCPY_FROM_USER
 	select ARCH_HAS_STRNLEN_USER