Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -93,7 +93,7 @@ INSTALL_LIB=\
   src/ocamlbuildlib.cma \
   src/ocamlbuild.cmo \
   src/ocamlbuild_pack.cmi \
-  $(EXTRA_CMO:.cmo=.cmi)
+  $(EXTRA_CMO) $(EXTRA_CMO:.cmo=.cmi)
 
 INSTALL_LIB_OPT=\
   src/ocamlbuildlib.cmxa src/ocamlbuildlib$(EXT_LIB) \