diff --git a/src/guard.c b/src/guard.c
index 1f2ee7f3f..a7fa1a97a 100644
--- a/src/guard.c
+++ b/src/guard.c
@@ -72,6 +72,7 @@ void setguard(unit * u, bool enabled)
     } else {
         assert(!fval(u, UFL_MOVED));
         assert(u->status < ST_FLEE);
+        assert(u->region->land);
         fset(u, UFL_GUARD);
         fset(u->region, RF_GUARDED);
     }
diff --git a/src/guard.test.c b/src/guard.test.c
index 1ffd1b4da..cc59af4d8 100644
--- a/src/guard.test.c
+++ b/src/guard.test.c
@@ -143,7 +143,7 @@ static void test_update_guard(CuTest * tc)
     t_plain = test_create_terrain("plain", LAND_REGION);
     itype = it_get_or_create(rt_get_or_create("sword"));
     new_weapontype(itype, 0, frac_zero, NULL, 0, 0, 0, SK_MELEE, 2);
-    r = test_create_region(0, 0, t_ocean);
+    r = test_create_region(0, 0, t_plain);
     ug = test_create_unit(test_create_faction(0), r);
     i_change(&ug->items, itype, 1);
     set_level(ug, SK_MELEE, 2);