diff --git a/changelog.txt b/changelog.txt
index 9cc5283ca..ce8bfca52 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -18,6 +18,7 @@ Engine changes
 * Fix sol.input.get_mouse_coordinates() (#734).
 * Fix straight movement precision.
 * Fix sword tapping sound still played when the game is suspended (#797).
+* Fix hero:set_invincible() not working without duration (#805).
 * Fix custom_entity:set_can_traverse_ground() not working for some grounds (#794).
 * Fix custom entity collisions not detected for entities that do not move (#671).
 * Fix creating an entity with the same name as another one just removed (#795).
diff --git a/src/entities/Hero.cpp b/src/entities/Hero.cpp
index 1118a3cd3..a431c28da 100644
--- a/src/entities/Hero.cpp
+++ b/src/entities/Hero.cpp
@@ -2011,7 +2011,7 @@ void Hero::set_invincible(bool invincible, uint32_t duration) {
   this->invincible = invincible;
   this->end_invincible_date = 0;
   if (invincible) {
-    this->end_invincible_date = System::now() + duration;
+    this->end_invincible_date = (duration == 0) ? 0 : System::now() + duration;
   }
 }
 
@@ -2020,8 +2020,9 @@ void Hero::set_invincible(bool invincible, uint32_t duration) {
  */
 void Hero::update_invincibility() {
 
-  if (is_invincible()
-      && System::now() >= end_invincible_date) {
+  if (is_invincible() &&
+      end_invincible_date != 0 &&
+      System::now() >= end_invincible_date) {
     set_invincible(false, 0);
   }
 }
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index ec5d4b4e5..f7f0ed1e6 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -19,6 +19,7 @@ set(lua_test_maps
   "bugs/794_custom_entity_set_can_traverse_ground"
   "bugs/795_recreate_entity_same_name"
   "bugs/796_map_get_entities_by_type"
+  "bugs/805_hero_set_invincible"
   "bugs/807_cannot_traverse_own_ground"
 )
 
diff --git a/tests/testing_quest/data/maps/bugs/805_hero_set_invincible.dat b/tests/testing_quest/data/maps/bugs/805_hero_set_invincible.dat
new file mode 100644
index 000000000..5d70a3f6e
--- /dev/null
+++ b/tests/testing_quest/data/maps/bugs/805_hero_set_invincible.dat
@@ -0,0 +1,26 @@
+properties{
+  x = 0,
+  y = 0,
+  width = 320,
+  height = 240,
+  min_layer = 0,
+  max_layer = 2,
+  tileset = "castle",
+}
+
+tile{
+  layer = 0,
+  x = 0,
+  y = 0,
+  width = 320,
+  height = 240,
+  pattern = "3",
+}
+
+destination{
+  layer = 0,
+  x = 24,
+  y = 29,
+  direction = 1,
+}
+
diff --git a/tests/testing_quest/data/maps/bugs/805_hero_set_invincible.lua b/tests/testing_quest/data/maps/bugs/805_hero_set_invincible.lua
new file mode 100644
index 000000000..cc35ccd01
--- /dev/null
+++ b/tests/testing_quest/data/maps/bugs/805_hero_set_invincible.lua
@@ -0,0 +1,25 @@
+local map = ...
+
+function map:on_started()
+
+  -- Set invincible with no limit.
+  hero:set_invincible(true)
+  assert(hero:is_invincible())
+
+  sol.timer.start(10, function()
+    assert(hero:is_invincible())
+
+    -- Stop invincibility.
+    hero:set_invincible(false)
+    assert(not hero:is_invincible())
+
+    -- Set invincible again, this time with a limit.
+    hero:set_invincible(true, 10)
+    assert(hero:is_invincible())
+
+    sol.timer.start(20, function()
+      assert(not hero:is_invincible())
+      sol.main.exit()
+    end)
+  end)
+end
diff --git a/tests/testing_quest/data/project_db.dat b/tests/testing_quest/data/project_db.dat
index 6552b9d40..f0c700775 100644
--- a/tests/testing_quest/data/project_db.dat
+++ b/tests/testing_quest/data/project_db.dat
@@ -14,6 +14,7 @@ map{ id = "bugs/781_assert_teletransporter_same_map", description = "#781: Asser
 map{ id = "bugs/794_custom_entity_set_can_traverse_ground", description = "#794: custom_entity:set_can_traverse_ground(\"traversable\", false) does not work" }
 map{ id = "bugs/795_recreate_entity_same_name", description = "#795: Cannot create an entity with the same name as another one just removed" }
 map{ id = "bugs/796_map_get_entities_by_type", description = "#796: Add map:get_entities_by_type()" }
+map{ id = "bugs/805_hero_set_invincible", description = "#805: hero:set_invincible() not working" }
 map{ id = "bugs/807_cannot_traverse_own_ground", description = "#807: Entity stuck if cannot traverse its own ground" }
 map{ id = "dynamic_tile_tests", description = "Dynamic tile tests" }
 map{ id = "jumper_tests", description = "Jumper tests" }