diff --git a/lib/Makefile b/lib/Makefile
index 7ce04da..c347d6f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -29,8 +29,14 @@ $(NATIVELIB): $(NATIVEOBJS)
 	$(OCAMLOPT) -a -o $(NATIVELIB) $(NATIVEOBJS)
 
 install:
-	cp $(INTERFACES) $(BYTELIB) $(NATIVELIB) $(NATIVELIB:.cmxa=.$(LIBEXT)) $(OCAMLLIB)
-	cd $(OCAMLLIB); $(RANLIB) $(NATIVELIB:.cmxa=.$(LIBEXT))
+	cp $(INTERFACES) $(BYTELIB) $(OCAMLLIB)
+	if [ -x /usr/bin/ocamlopt ]; then \
+		cp $(NATIVELIB) $(NATIVELIB:.cmxa=.$(LIBEXT)) $(OCAMLLIB); \
+		cd $(OCAMLLIB); \
+		$(RANLIB) $(NATIVELIB:.cmxa=.$(LIBEXT));  \
+	else \
+		true; \
+	fi
 
 .SUFFIXES: .mli .ml .cmi .cmo .cmx