diff --git a/sys/geom/geom_kern.c b/sys/geom/geom_kern.c
index a346b6a0d8f..762a1fd6986 100644
--- a/sys/geom/geom_kern.c
+++ b/sys/geom/geom_kern.c
@@ -220,6 +220,7 @@ SYSCTL_PROC(_kern_geom, OID_AUTO, conftxt, CTLTYPE_STRING|CTLFLAG_RD,
 	0, 0, sysctl_kern_geom_conftxt, "",
 	"Dump the GEOM config in txt");
 
+TUNABLE_INT("kern.geom.debugflags", &g_debugflags);
 SYSCTL_INT(_kern_geom, OID_AUTO, debugflags, CTLFLAG_RW,
 	&g_debugflags, 0, "");