diff --git a/pkgs/os-specific/linux/kernel/common-config.nix b/pkgs/os-specific/linux/kernel/common-config.nix
index 3f623a66a512..1fcb2300ca31 100644
--- a/pkgs/os-specific/linux/kernel/common-config.nix
+++ b/pkgs/os-specific/linux/kernel/common-config.nix
@@ -280,17 +280,17 @@ with stdenv.lib;
   ''}
 
   # Virtualisation.
-  PARAVIRT y
+  PARAVIRT? y
   ${if versionAtLeast version "3.10" then ''
     HYPERVISOR_GUEST y
   '' else ''
-    PARAVIRT_GUEST y
+    PARAVIRT_GUEST? y
   ''}
-  KVM_GUEST y
+  KVM_GUEST? y
   ${optionalString (versionOlder version "3.7") ''
-    KVM_CLOCK y
+    KVM_CLOCK? y
   ''}
-  XEN y
+  XEN? y
   XEN_DOM0? y
   KSM y
   ${optionalString (!stdenv.is64bit) ''