diff --git a/src/c/ticTacToe.c b/src/c/ticTacToe.c
index 5eab4a2..f8d5e1a 100644
--- a/src/c/ticTacToe.c
+++ b/src/c/ticTacToe.c
@@ -45,4 +45,5 @@ bool validateUserInput(int row, int col){
             return true;
         }
     }
+    return false;
 }
\ No newline at end of file
diff --git a/test/c/test_ticTacToe.c b/test/c/test_ticTacToe.c
index d912a7a..bb0509c 100644
--- a/test/c/test_ticTacToe.c
+++ b/test/c/test_ticTacToe.c
@@ -24,4 +24,18 @@ void test_ticTacToe_validUserInput(void)
     TEST_ASSERT_EQUAL_INT(true, result);
 }
 
+void test_ticTacToe_invalidUserInput(void)
+{
+    /* arrange */
+    bool result;
+    int row = 1, col = 3;
+
+    /* act */
+    result = validateUserInput(row, col);
+
+    /* assert */
+    TEST_ASSERT_EQUAL_INT(false, result);
+}
+
+
 #endif // TEST
\ No newline at end of file