diff --git a/Makefile.inc b/Makefile.inc
index adc41bf..bcf0e6e 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -59,7 +59,7 @@
 
 #######################################################################
 # Add source classes and their build options
-classes-y := ramstage romstage driver smm
+classes-y := ramstage romstage driver smm cpu_microcode
 
 romstage-c-ccopts:=-D__PRE_RAM__
 romstage-S-ccopts:=-D__PRE_RAM__