diff --git a/src/riichi.erl b/src/riichi.erl
index ad36006..2004548 100644
--- a/src/riichi.erl
+++ b/src/riichi.erl
@@ -89,6 +89,10 @@ score_hand(#hand{tiles=T, sets=_S}=_H, BaseFu, Limit) ->
         _DaiSanGen = case sets:is_subset(sets:from_list([{3, #tile{suit=dragon, value=red}}, {3, #tile{suit=dragon, value=white}}, {3, #tile{suit=dragon, value=green}}]), sets:from_list(find_sets(T))) of
             true -> 13;
             _ -> 0
+        end,
+        _Kokushi_Musou = case (lists:flatten([lists:duplicate(12, 1), [2]]) == lists:sort([C || {C, _T} <- find_sets(T)])) and (not lists:any(fun(#tile{value=V}) -> lists:member(V, lists:seq(2,8)) end, T)) of
+            true -> 13;
+            _ -> 0
         end
     ],
     score(lists:sum(Fu), lists:sum(Han), Limit).
diff --git a/test/riichi_tests.erl b/test/riichi_tests.erl
index a602b65..254d2d4 100644
--- a/test/riichi_tests.erl
+++ b/test/riichi_tests.erl
@@ -93,3 +93,13 @@ score_hand_dai_san_gan_test() ->
             lists:duplicate(2, #tile{suit=wind, value=north})])
     },
     ?assertEqual(riichi:score_hand(Hand, 30), 8000).
+
+score_hand_kokushi_musou_test() ->
+    Hand = #hand{
+        tiles = lists:flatten([
+            [#tile{suit=S, value=V} || S <- [pin, sou, man], V <- [1,9]], % Terminals
+            [#tile{suit=wind, value=V} || V <- [east, south, west, north]], % Winds
+            [#tile{suit=dragon, value=V} || V <- [red, white, green]], % Dragons
+            [#tile{suit=pin, value=1}]])
+    },
+    ?assertEqual(riichi:score_hand(Hand, 30), 8000).