diff --git a/exercises/practice/state-of-tic-tac-toe/.meta/tests.toml b/exercises/practice/state-of-tic-tac-toe/.meta/tests.toml
index 8fc25e21..5f574b2a 100644
--- a/exercises/practice/state-of-tic-tac-toe/.meta/tests.toml
+++ b/exercises/practice/state-of-tic-tac-toe/.meta/tests.toml
@@ -99,3 +99,9 @@ reimplements = "b1dc8b13-46c4-47db-a96d-aa90eedc4e8d"
 
 [4801cda2-f5b7-4c36-8317-3cdd167ac22c]
 description = "Invalid boards -> Invalid board: players kept playing after a win"
+
+[5a84757a-fc86-4328-aec9-a5759e6ed35d]
+description = "Invalid boards -> Invalid board: O kept playing after X wins"
+
+[cf25543d-583a-4656-b9ab-f82dc00a4a02]
+description = "Invalid boards -> Invalid board: X kept playing after O wins"
diff --git a/exercises/practice/state-of-tic-tac-toe/example/state_of_tic_tac_toe.d b/exercises/practice/state-of-tic-tac-toe/example/state_of_tic_tac_toe.d
index 7a335f18..d3f121cd 100644
--- a/exercises/practice/state-of-tic-tac-toe/example/state_of_tic_tac_toe.d
+++ b/exercises/practice/state-of-tic-tac-toe/example/state_of_tic_tac_toe.d
@@ -51,6 +51,16 @@ pure State gamestate(immutable string[] board)
             throw new Exception("Impossible board: game should have ended after the game was won");
         }
 
+        if (win_x && count_o == count_x)
+        {
+            throw new Exception("Impossible board: O kept playing after X wins");
+        }
+
+        if (win_o && count_x > count_o)
+        {
+            throw new Exception("Impossible board: X kept playing after O wins");
+        }
+
         return State.win;
     }
 
diff --git a/exercises/practice/state-of-tic-tac-toe/source/state_of_tic_tac_toe.d b/exercises/practice/state-of-tic-tac-toe/source/state_of_tic_tac_toe.d
index 7fa19375..3c1a3eda 100644
--- a/exercises/practice/state-of-tic-tac-toe/source/state_of_tic_tac_toe.d
+++ b/exercises/practice/state-of-tic-tac-toe/source/state_of_tic_tac_toe.d
@@ -288,5 +288,25 @@ unittest
             ];
             assertThrown(gamestate(board));
         }
+
+        // Invalid boards-Invalid board: O kept playing after X wins
+        {
+            immutable string[] board = [
+                "OO ",
+                "XXX",
+                " O ",
+            ];
+            assertThrown(gamestate(board));
+        }
+
+        // Invalid boards-Invalid board: X kept playing after O wins
+        {
+            immutable string[] board = [
+                "XX ",
+                "OOO",
+                " XX",
+            ];
+            assertThrown(gamestate(board));
+        }
     }
 }