Won't let me end a loop

[mzmingle]

Here's my code now, and the error message:

Error:
Traceback (most recent call last):
  File "C:\Users\...\noughts and crosses.py", line 72, in <module>
    gameRun = checkX()
  File "C:\Users\...\noughts and crosses.py", line 54, in checkX
    return gameRun
UnboundLocalError: local variable 'gameRun' referenced before assignment

grid = [1, 2, 3,
        4, 5, 6,
        7, 8, 9]

gridSave = [1, 2, 3,
            4, 5, 6,
            7, 8, 9]

gameRun = True

def show():
    print(grid[0], '|', grid[1], '|', grid[2])
    print('----------')
    print(grid[3], '|', grid[4], '|', grid[5])
    print('----------')
    print(grid[6], '|', grid[7], '|', grid[8])

def checkX():
    
    if grid[0] == 'X' and grid[1] == 'X' and grid[2] == 'X':
        print("Player one wins!")
        gameRun = False
    
    if grid[3] == 'X' and grid[4] == 'X' and grid[5] == 'X':
        print("Player one wins!")
        gameRun = False

    if grid[6] == 'X' and grid[7] == 'X' and grid[8] == 'X':
        print("Player one wins!")
        gameRun = False
        

    if grid[0] == 'X' and grid[3] == 'X' and grid[6] == 'X':
        print("Player one wins!")
        gameRun = False

    if grid[1] == 'X' and grid[4] == 'X' and grid[7] == 'X':
        print("Player one wins!")
        gameRun = False

    if grid[2] == 'X' and grid[5] == 'X' and grid[8] == 'X':
        print("Player one wins!")
        gameRun = False
        

    if grid[0] == 'X' and grid[4] == 'X' and grid[8] == 'X':
        print("Player one wins!")
        gameRun = False

    if grid[2] == 'X' and grid[4] == 'X' and grid[6] == 'X':
        print("Player one wins!")
        gameRun = False

    return gameRun
        

show()

while gameRun == True:

    inputX = input("Player one, please select a spot: ")
    inputX = (int(inputX) - 1)
    
    if grid[inputX] != 'X' and grid[inputX] != 'O':
        grid[inputX] = 'X'

    else:
        print("This space is taken!")

    show()

    gameRun = checkX()

    inputY = input("Player two, please select a spot: ")
    inputY = (int(inputY) - 1)
    
    if grid[inputY] != 'X' and grid[inputY] != 'O':
        grid[inputY] = 'O'

    else:
        print("This space is taken!")

    show()

    

if gameRun == False: 

    print("The game is now finished! Play again!")
    grid = gridSave
    print(grid)