diff --git a/src/guard.c b/src/guard.c
index 07640452c..1f2ee7f3f 100644
--- a/src/guard.c
+++ b/src/guard.c
@@ -34,6 +34,9 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 guard_t can_start_guarding(const unit * u)
 {
+    if (!u->region->land) {
+        return E_GUARD_TERRAIN;
+    }
     if (u->status >= ST_FLEE || fval(u, UFL_FLEEING))
         return E_GUARD_FLEEING;
     /* Monster der Monsterpartei duerfen immer bewachen */
diff --git a/src/guard.h b/src/guard.h
index 101369f40..5a717d92d 100644
--- a/src/guard.h
+++ b/src/guard.h
@@ -12,7 +12,7 @@ extern "C" {
     struct unit;
     struct region;
     
-    typedef enum { E_GUARD_OK, E_GUARD_UNARMED, E_GUARD_NEWBIE, E_GUARD_FLEEING } guard_t;
+    typedef enum { E_GUARD_OK, E_GUARD_UNARMED, E_GUARD_NEWBIE, E_GUARD_FLEEING, E_GUARD_TERRAIN } guard_t;
 
     guard_t can_start_guarding(const struct unit * u);
     void update_guards(void);
diff --git a/src/guard.test.c b/src/guard.test.c
index 17aa2891c..1ffd1b4da 100644
--- a/src/guard.test.c
+++ b/src/guard.test.c
@@ -7,7 +7,9 @@
 #include <kernel/config.h>
 #include <kernel/faction.h>
 #include <kernel/unit.h>
+#include <kernel/order.h>
 #include <kernel/race.h>
+#include <kernel/terrain.h>
 #include <kernel/item.h>
 #include <kernel/region.h>
 
@@ -128,14 +130,117 @@ static void test_guard_monsters(CuTest * tc)
     test_cleanup();
 }
 
+static void test_update_guard(CuTest * tc)
+/* https://bugs.eressea.de/view.php?id=2292 */
+{
+    unit *ug;
+    region *r;
+    item_type *itype;
+    const struct terrain_type *t_ocean, *t_plain;
+
+    test_setup();
+    t_ocean = test_create_terrain("ocean", SEA_REGION);
+    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);
+    ug = test_create_unit(test_create_faction(0), r);
+    i_change(&ug->items, itype, 1);
+    set_level(ug, SK_MELEE, 2);
+    setguard(ug, true);
+    CuAssertIntEquals(tc, 1, armedmen(ug, false));
+    CuAssertTrue(tc, is_guard(ug));
+
+    terraform_region(r, t_ocean);
+    update_guards();
+    CuAssertTrue(tc, ! is_guard(ug));
+
+    test_cleanup();
+}
+
+static void test_guard_on(CuTest * tc)
+{
+    unit *ug;
+    region *r;
+    item_type *itype;
+    terrain_type *t_ocean, *t_plain;
+
+    test_setup();
+    t_ocean = test_create_terrain("ocean", SEA_REGION);
+    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_plain);
+    ug = test_create_unit(test_create_faction(0), r);
+    i_change(&ug->items, itype, 1);
+    set_level(ug, SK_MELEE, 2);
+    ug->thisorder = create_order(K_GUARD, ug->faction->locale, NULL);
+
+    setguard(ug, false);
+    CuAssertIntEquals(tc, E_GUARD_OK, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, is_guard(ug));
+
+    terraform_region(r, t_ocean);
+
+    setguard(ug, false);
+    CuAssertIntEquals(tc, E_GUARD_TERRAIN, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, !is_guard(ug));
+    CuAssertPtrNotNull(tc, test_find_messagetype(ug->faction->msgs, "error2"));
+
+    setguard(ug, false);
+    t_ocean->flags &= ~ SEA_REGION;
+    CuAssertIntEquals(tc, E_GUARD_TERRAIN, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, !is_guard(ug));
+    CuAssertPtrNotNull(tc, test_find_messagetype(ug->faction->msgs, "error_onlandonly"));
+
+    terraform_region(r, t_plain);
+
+    i_change(&ug->items, itype, -1);
+    CuAssertIntEquals(tc, E_GUARD_UNARMED, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, !is_guard(ug));
+    CuAssertPtrNotNull(tc, test_find_messagetype(ug->faction->msgs, "unit_unarmed"));
+    i_change(&ug->items, itype, 1);
+
+    test_clear_messages(ug->faction);
+    set_level(ug, SK_MELEE, 0);
+    CuAssertIntEquals(tc, E_GUARD_UNARMED, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, !is_guard(ug));
+    CuAssertPtrNotNull(tc, test_find_messagetype(ug->faction->msgs, "unit_unarmed"));
+    set_level(ug, SK_MELEE, 2);
+
+    ug->status = ST_FLEE;
+    CuAssertIntEquals(tc, E_GUARD_FLEEING, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, !is_guard(ug));
+    CuAssertPtrNotNull(tc, test_find_messagetype(ug->faction->msgs, "error320"));
+    ug->status = ST_FIGHT;
+
+    config_set("NewbieImmunity", "5");
+    CuAssertIntEquals(tc, E_GUARD_NEWBIE, can_start_guarding(ug));
+    guard_on_cmd(ug, ug->thisorder);
+    CuAssertTrue(tc, !is_guard(ug));
+    CuAssertPtrNotNull(tc, test_find_messagetype(ug->faction->msgs, "error304"));
+    config_set("NewbieImmunity", NULL);
+
+    test_clear_messages(ug->faction);
+    test_cleanup();
+}
+
 CuSuite *get_guard_suite(void)
 {
     CuSuite *suite = CuSuiteNew();
     SUITE_ADD_TEST(suite, test_is_guarded);
     SUITE_ADD_TEST(suite, test_is_guard);
     SUITE_ADD_TEST(suite, test_guard_unskilled);
+    SUITE_ADD_TEST(suite, test_guard_on);
     SUITE_ADD_TEST(suite, test_guard_armed);
     SUITE_ADD_TEST(suite, test_guard_unarmed);
     SUITE_ADD_TEST(suite, test_guard_monsters);
+    SUITE_ADD_TEST(suite, test_update_guard);
     return suite;
 }
diff --git a/src/laws.c b/src/laws.c
index 253b45b89..dfbd163cb 100644
--- a/src/laws.c
+++ b/src/laws.c
@@ -2686,31 +2686,34 @@ int guard_on_cmd(unit * u, struct order *ord)
         return 0;
     }
 
-    if (fval(u->region->terrain, SEA_REGION)) {
-        cmistake(u, ord, 2, MSG_EVENT);
+    if (fval(u, UFL_MOVED)) {
+        cmistake(u, ord, 187, MSG_EVENT);
+    }
+    else if (fval(u_race(u), RCF_ILLUSIONARY)
+        || u_race(u) == get_race(RC_SPELL)) {
+        cmistake(u, ord, 95, MSG_EVENT);
     }
     else {
-        if (fval(u, UFL_MOVED)) {
-            cmistake(u, ord, 187, MSG_EVENT);
+        int err = can_start_guarding(u);
+        if (err == E_GUARD_OK) {
+            setguard(u, true);
         }
-        else if (fval(u_race(u), RCF_ILLUSIONARY)
-            || u_race(u) == get_race(RC_SPELL)) {
-            cmistake(u, ord, 95, MSG_EVENT);
+        else if (err == E_GUARD_TERRAIN) {
+            if (fval(u->region->terrain, SEA_REGION)) {
+                cmistake(u, ord, 2, MSG_EVENT);
+            }
+            else {
+                ADDMSG(&u->faction->msgs, msg_feedback(u, ord, "error_onlandonly", ""));
+            }
         }
-        else {
-            int err = can_start_guarding(u);
-            if (err == E_GUARD_OK) {
-                setguard(u, true);
-            }
-            else if (err == E_GUARD_UNARMED) {
-                ADDMSG(&u->faction->msgs, msg_feedback(u, ord, "unit_unarmed", ""));
-            }
-            else if (err == E_GUARD_FLEEING) {
-                cmistake(u, ord, 320, MSG_EVENT);
-            }
-            else if (err == E_GUARD_NEWBIE) {
-                cmistake(u, ord, 304, MSG_EVENT);
-            }
+        else if (err == E_GUARD_UNARMED) {
+            ADDMSG(&u->faction->msgs, msg_feedback(u, ord, "unit_unarmed", ""));
+        }
+        else if (err == E_GUARD_FLEEING) {
+            cmistake(u, ord, 320, MSG_EVENT);
+        }
+        else if (err == E_GUARD_NEWBIE) {
+            cmistake(u, ord, 304, MSG_EVENT);
         }
     }
     return 0;