diff --git a/sys/geom/geom.h b/sys/geom/geom.h
index 15c253bc9e5d..7bcceccbf426 100644
--- a/sys/geom/geom.h
+++ b/sys/geom/geom.h
@@ -212,7 +212,7 @@ int g_handleattr_off_t(struct bio *bp, const char *attribute, off_t val);
 struct g_consumer * g_new_consumer(struct g_geom *gp);
 struct g_geom * g_new_geomf(struct g_class *mp, const char *fmt, ...);
 struct g_provider * g_new_providerf(struct g_geom *gp, const char *fmt, ...);
-void g_sanity(void *ptr);
+void g_sanity(void const *ptr);
 void g_spoil(struct g_provider *pp, struct g_consumer *cp);
 int g_std_access(struct g_provider *pp, int dr, int dw, int de);
 void g_std_done(struct bio *bp);
diff --git a/sys/geom/geom_subr.c b/sys/geom/geom_subr.c
index d23105ebf3d0..51702d261f4e 100644
--- a/sys/geom/geom_subr.c
+++ b/sys/geom/geom_subr.c
@@ -761,7 +761,7 @@ g_getattr__(const char *attr, struct g_consumer *cp, void *var, int len)
  */
 
 void
-g_sanity(void *ptr)
+g_sanity(void const *ptr)
 {
 	struct g_class *mp;
 	struct g_geom *gp;