diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index 03a6afc4f6..eb36259085 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -519,6 +519,9 @@
 #    ifdef byte
 #      undef byte
 #    endif
+#    ifdef resolve_ip
+#      undef resolve_ip
+#    endif
 
 #  endif /* MSDOS */