--- library/Makefile
+++ library/Makefile
@@ -42,9 +42,9 @@
 
 libpolarssl.a: $(OBJS)
 	echo "  AR    $@"
-	ar r $@ $(OBJS)
+	$(AR) r $@ $(OBJS)
 	echo "  RL    $@"
-	ranlib $@
+	$(RANLIB) $@
 
 $(LIB_SO_VERSION): $(OBJS)
 	echo "  LD    $@"