diff --git a/core/scripts/tests/common.lua b/core/scripts/tests/common.lua
index f6aebd8db..35145e0f0 100755
--- a/core/scripts/tests/common.lua
+++ b/core/scripts/tests/common.lua
@@ -1427,3 +1427,35 @@ function test_faction_flags()
 	f.flags = 42
 	assert_equal(42, f.flags)
 end
+
+function test_bug_1738_build_castle_e3()
+  local r = region.create(0, 0, "plain")    
+  local f = faction.create("bug_1738@eressea.de", "human", "de")
+
+  local c = building.create(r, "castle")
+  c.size = 228
+
+  local u1 = unit.create(f, r, 1)
+  u1:set_skill("building", 5)
+  u1:add_item("stone", 10000)
+
+  local u2 = unit.create(f, r, 32)
+  u2:set_skill("building", 3)
+  u2:add_item("stone", 10000)
+
+  u1:clear_orders()
+  u1:add_order("MACHE BURG " .. itoa36(c.id))
+  -- castle now has size 229.
+  u2:clear_orders()
+  u2:add_order("MACHE BURG " .. itoa36(c.id))
+  -- 32 * 3 makes 96 talent points.
+  -- from size 229 to size 250 needs 21 * 3 = 63 points, rest 33.
+  -- 33/4 makes 8 points, resulting size is 258.
+
+  process_orders()
+  init_reports()
+  write_report(f)
+  -- resulting size should be 250 because unit 2
+  -- does not have the needed minimum talent.
+  assert_equal(c.size, 250)
+end