diff --git a/src/main/c/Minesweeper/minesweeper_start.c b/src/main/c/Minesweeper/minesweeper_start.c
index 19b4e50..fedb818 100644
--- a/src/main/c/Minesweeper/minesweeper_start.c
+++ b/src/main/c/Minesweeper/minesweeper_start.c
@@ -247,16 +247,17 @@ void open_empty_space(Minesweeper_Board *board, int tile, int index){
     }
 }
 
-int is_Valid_tile(Minesweeper_Board *board, int tile, int i){
+//0 = up-left, 1 = down-left, 2 = mid-left, 3 = up-mid, 4 = down-mid, 5 = mid-right, 6 = up-right, 7 = down-right
+int is_Valid_tile(Minesweeper_Board *board, int tile, int direction){
     int check_tile = tile;
     
-    if(i < 3){if(tile % board->width == 0){return -1;}
+    if(direction < 3){if(tile % board->width == 0){return -1;}
     else{check_tile -= 1;}}
-    if(i > 4){if(tile % board->width + 1 == board->width){return -1;}
+    if(direction > 4){if(tile % board->width + 1 == board->width){return -1;}
     else{check_tile += 1;}}
-    if(i % 3 == 0){if(tile / board->width == 0){return -1;}
+    if(direction % 3 == 0){if(tile / board->width == 0){return -1;}
     else{check_tile -= board->width;}}
-    if(i % 3 == 1){if(tile / board->width + 1 == height){return -1;}
+    if(direction % 3 == 1){if(tile / board->width + 1 == height){return -1;}
     else{check_tile += board->width;}}
 
     return check_tile;
diff --git a/src/main/c/Minesweeper/minesweeper_start.h b/src/main/c/Minesweeper/minesweeper_start.h
index c37d731..750003e 100644
--- a/src/main/c/Minesweeper/minesweeper_start.h
+++ b/src/main/c/Minesweeper/minesweeper_start.h
@@ -1,5 +1,6 @@
 #ifndef MINESWEEPER_START_H
 #define MINESWEEPER_START_H
+#include <stdbool.h>
 
 typedef struct Minesweeper_Board{
     unsigned int width;
@@ -10,11 +11,10 @@ typedef struct Minesweeper_Board{
     int *bombs;
 }Minesweeper_Board;
 
-
 void minesweeper_start();
 Minesweeper_Board initialize_minesweeper();
 bool array_contains_value(int *array, int bomb, int length);
 int number_of_bombs(Minesweeper_Board *board, int tile);
-
+int is_Valid_tile(Minesweeper_Board *board, int tile, int direction);
 
 #endif // MINESWEEPER_START_H
\ No newline at end of file
diff --git a/test/Minesweeper/test_is_Valid_tile.c b/test/Minesweeper/test_is_Valid_tile.c
new file mode 100644
index 0000000..65082e2
--- /dev/null
+++ b/test/Minesweeper/test_is_Valid_tile.c
@@ -0,0 +1,24 @@
+#ifdef TEST
+#include "unity.h"
+#include "../../src/main/c/Minesweeper/minesweeper_start.h"
+
+
+void setUp(void){}
+void tearDown(void){}
+
+
+void test_detect_not_valid_tile(void){
+    /* arrange */
+    Minesweeper_Board board = initialize_minesweeper();
+    int tile = 0;
+    int direction = 1;
+    int result;
+
+    /* act */
+    result = is_Valid_tile(&board, tile, direction);
+
+    /* assert */
+    TEST_ASSERT_EQUAL_INT(-1, result);//not valid tile
+}
+
+#endif // TEST
\ No newline at end of file