diff --git a/Kbuild b/Kbuild
index 79dff01..12409ea 100644
--- a/Kbuild
+++ b/Kbuild
@@ -2930,6 +2930,7 @@
 
 #Flag to enable/disable HOST_OPCLASS
 cppflags-$(CONFIG_HOST_OPCLASS) += -DHOST_OPCLASS
+cppflags-$(CONFIG_HOST_OPCLASS) += -DHOST_OPCLASS_EXT
 
 #Flag to enable/disable TARGET_11D_SCAN
 cppflags-$(CONFIG_TARGET_11D_SCAN) += -DTARGET_11D_SCAN