diff --git a/arch/um/Makefile-x86_64 b/arch/um/Makefile-x86_64
index dffd118..9558a7c 100644
--- a/arch/um/Makefile-x86_64
+++ b/arch/um/Makefile-x86_64
@@ -11,6 +11,7 @@
 CHECKFLAGS  += -m64
 AFLAGS += -m64
 LDFLAGS += -m elf_x86_64
+CPPFLAGS += -m64
 
 ELF_ARCH := i386:x86-64
 ELF_FORMAT := elf64-x86-64
diff --git a/arch/um/kernel/vmlinux.lds.S b/arch/um/kernel/vmlinux.lds.S
index 72acdce..f8aeb44 100644
--- a/arch/um/kernel/vmlinux.lds.S
+++ b/arch/um/kernel/vmlinux.lds.S
@@ -1,5 +1,3 @@
-/* in case the preprocessor is a 32bit one */
-#undef i386
 #ifdef CONFIG_LD_SCRIPT_STATIC
 #include "uml.lds.S"
 #else