diff --git a/scripts/tests/common.lua b/scripts/tests/common.lua
index c39f2ce30..670060816 100644
--- a/scripts/tests/common.lua
+++ b/scripts/tests/common.lua
@@ -380,6 +380,21 @@ function test_events()
   assert(fail==0)
 end
 
+function test_renumber_ship()
+    local r = region.create(0, 0, "plain")
+    local f = faction.create("noreply4@eressea.de", "human", "de")
+    local u = unit.create(f, r)
+    local s = ship.create(r, config.ships[1])
+    u.ship = s
+    u:add_order("NUMMER SCHIFF 1")
+    process_orders()
+    assert_equal(1, s.id)
+    u:clear_orders()
+    u:add_order("NUMMER SCHIFF 2")
+    process_orders()
+    assert_equal(2, s.id)
+end
+
 function test_recruit2()
     local r = region.create(0, 0, "plain")
     local f = faction.create("noreply4@eressea.de", "human", "de")
diff --git a/scripts/tests/xmas.lua b/scripts/tests/xmas.lua
index 153052d5a..7ac4ce731 100644
--- a/scripts/tests/xmas.lua
+++ b/scripts/tests/xmas.lua
@@ -7,7 +7,7 @@ function setup()
     eressea.settings.set("nmr.timeout", "0")
     eressea.settings.set("rules.grow.formula", "0")
     eressea.settings.set("rules.peasants.growth.factor", "0")
-    eressea.settings.set("volcano.active.percent", "4")
+    eressea.settings.set("volcano.active.percent", "0")
 end
 
 function test_snowglobe_fail()
diff --git a/src/renumber.test.c b/src/renumber.test.c
index 9ab6b1e7b..6c3f0f17b 100644
--- a/src/renumber.test.c
+++ b/src/renumber.test.c
@@ -102,6 +102,27 @@ static void test_renumber_ship(CuTest *tc) {
     test_cleanup();
 }
 
+static void test_renumber_ship_twice(CuTest *tc) {
+    unit *u;
+    int uno, no;
+    const struct locale *lang;
+
+    test_setup_ex(tc);
+    u = test_create_unit(test_create_faction(0), test_create_region(0, 0, 0));
+    u->ship = test_create_ship(u->region, 0);
+    no = u->ship->no;
+    uno = (no > 1) ? no - 1 : no + 1;
+    lang = u->faction->locale;
+    u->thisorder = create_order(K_NUMBER, lang, "%s %s", LOC(lang, parameters[P_SHIP]), itoa36(uno));
+    renumber_cmd(u, u->thisorder);
+    CuAssertIntEquals(tc, uno, u->ship->no);
+    free_order(u->thisorder);
+    u->thisorder = create_order(K_NUMBER, lang, "%s %s", LOC(lang, parameters[P_SHIP]), itoa36(no));
+    renumber_cmd(u, u->thisorder);
+    CuAssertIntEquals(tc, no, u->ship->no);
+    test_cleanup();
+}
+
 static void test_renumber_ship_duplicate(CuTest *tc) {
     unit *u;
     faction *f;
@@ -204,6 +225,7 @@ CuSuite *get_renumber_suite(void)
     SUITE_ADD_TEST(suite, test_renumber_building);
     SUITE_ADD_TEST(suite, test_renumber_building_duplicate);
     SUITE_ADD_TEST(suite, test_renumber_ship);
+    SUITE_ADD_TEST(suite, test_renumber_ship_twice);
     SUITE_ADD_TEST(suite, test_renumber_ship_duplicate);
     SUITE_ADD_TEST(suite, test_renumber_faction);
     SUITE_ADD_TEST(suite, test_renumber_faction_duplicate);