diff --git a/Kconfig b/Kconfig
index 959dd986a6d02b7e9244f4eb9a0bd0ddf60c5ec5..e24b71e8dbecadf15e5f425677eb8f30fde2211e 100644
--- a/Kconfig
+++ b/Kconfig
@@ -31,16 +31,13 @@ menu "seL4 System"
         config ARCH_I386
             bool "x86"
 
-        config ARCH_X86_64
-            bool "x86_64"
-
         config ARCH_ARM
             bool "ARM"
     endchoice
 
 config ARCH_IA32
        bool
-       default y if ARCH_I386 || ARCH_X86_64
+       default y if ARCH_I386
 
     choice
         prompt "ARM CPU selection"
@@ -163,7 +160,7 @@ config ARCH_IA32
 
         config PLAT_PC99
             bool "PC99"
-            depends on ARCH_I386 || ARCH_X86_64
+            depends on ARCH_I386
             help
                 Support for PC99 based platform
     endchoice