diff --git a/sys/dev/mwl/if_mwl.c b/sys/dev/mwl/if_mwl.c
index bf669620b129..63a3e6bc0d77 100644
--- a/sys/dev/mwl/if_mwl.c
+++ b/sys/dev/mwl/if_mwl.c
@@ -281,11 +281,13 @@ struct mwltxrec {
  * that all BAR 1 operations are done in the "hal" and
  * there should be no reference to them here.
  */
+#ifdef MWL_DEBUG
 static __inline uint32_t
 RD4(struct mwl_softc *sc, bus_size_t off)
 {
 	return bus_space_read_4(sc->sc_io0t, sc->sc_io0h, off);
 }
+#endif
 
 static __inline void
 WR4(struct mwl_softc *sc, bus_size_t off, uint32_t val)