diff --git a/src/test/c/test_VierGewinnt.c b/src/test/c/test_VierGewinnt.c
index 73f89e0..9681ea7 100644
--- a/src/test/c/test_VierGewinnt.c
+++ b/src/test/c/test_VierGewinnt.c
@@ -73,7 +73,18 @@ void test_checkWin_Diagonal_X(void) {
 
 
 
+void test_checkWin_Diagonal_O(void) {
+    char board[6][7] = {
+        {'X', 'X', ' ', ' ', ' ', ' ', ' '},
+        {'O', 'O', 'O', 'X', ' ', ' ', ' '},
+        {' ', 'O', ' ', ' ', ' ', ' ', ' '},
+        {' ', 'X', 'O', 'X', 'X', ' ', ' '},
+        {' ', ' ', ' ','O', ' ', ' ', ' '},
+        {' ', ' ', ' ', ' ', ' ', 'X', ' '}
+    };
 
+    TEST_ASSERT_EQUAL_INT(1, checkWin(board, 'O'));  // Horizontale Gewinnsituation für 'X'
+}