diff --git a/arch/um/Kconfig.x86 b/arch/um/Kconfig.x86
index 5ee3280..62f2115 100644
--- a/arch/um/Kconfig.x86
+++ b/arch/um/Kconfig.x86
@@ -19,6 +19,9 @@
 	def_bool !64BIT
 	select HAVE_AOUT
 
+config X86_64
+	def_bool 64BIT
+
 config RWSEM_XCHGADD_ALGORITHM
 	def_bool X86_XADD