diff --git a/dGame/dComponents/InventoryComponent.cpp b/dGame/dComponents/InventoryComponent.cpp
index 8075579c7..a2798068c 100644
--- a/dGame/dComponents/InventoryComponent.cpp
+++ b/dGame/dComponents/InventoryComponent.cpp
@@ -2021,6 +2021,8 @@ void InventoryComponent::UpdateGroup(const GroupUpdate& groupUpdate) {
 		break;
 	}
 	case GroupUpdateCommand::ADD_LOT: {
+		// msgUpdateInventoryGroupContents (0x00ce1f50): a group holds at most 1000 LOTs
+		if (groupItr->lots.size() >= MaximumGroupLotCount) break;
 		groupItr->lots.insert(groupUpdate.lot);
 		break;
 	}
diff --git a/dGame/dComponents/InventoryComponent.h b/dGame/dComponents/InventoryComponent.h
index b9e1c107a..d7d7e1832 100644
--- a/dGame/dComponents/InventoryComponent.h
+++ b/dGame/dComponents/InventoryComponent.h
@@ -101,6 +101,7 @@ public:
 
 	static constexpr uint32_t MaximumGroupCount = 50;
 	static constexpr size_t MaximumGroupNameLength = 64; // UTF-16 characters
+	static constexpr size_t MaximumGroupLotCount = 1000;
 
 	static constexpr eReplicaComponentType ComponentType = eReplicaComponentType::INVENTORY;
 
diff --git a/tests/dGameTests/dComponentsTests/InventoryGroupTests.cpp b/tests/dGameTests/dComponentsTests/InventoryGroupTests.cpp
index c697950d0..e9a8376c6 100644
--- a/tests/dGameTests/dComponentsTests/InventoryGroupTests.cpp
+++ b/tests/dGameTests/dComponentsTests/InventoryGroupTests.cpp
@@ -88,3 +88,11 @@ TEST_F(InventoryGroupTests, ClearEmptiesAGroup) {
 	ASSERT_EQ(Groups().size(), 1u);
 	EXPECT_TRUE(Groups()[0].lots.empty());
 }
+
+TEST_F(InventoryGroupTests, AGroupHoldsAtMost1000Lots) {
+	Group("ADD", "user_group1", u"bricks");
+	for (LOT lot = 1; lot <= 1001; lot++) Contents("ADD", "user_group1", lot);
+
+	EXPECT_EQ(Groups()[0].lots.size(), 1000u);
+	EXPECT_FALSE(Groups()[0].lots.contains(1001));
+}