diff --git a/crypto_portfolio.py b/crypto_portfolio.py
index 6929b08..30e5c76 100644
--- a/crypto_portfolio.py
+++ b/crypto_portfolio.py
@@ -9,8 +9,12 @@ import mplfinance as mpf
 # a chave da API 'CHAVE_API_DEMO'
 if not os.path.exists('modulos/constantes.py'):
     chave_api = input('Introduza a chave da API Demo de CoinGecko: ')
-    with open('modulos/constantes.py', 'w') as f:
-        f.write(f'CHAVE_API_DEMO = \'{chave_api}\'\n')
+    if (not aux.validarChaveAPI(chave_api)):
+        print(f'erro na validação da chave API {chave_api}')
+        quit()
+    else:
+        with open('modulos/constantes.py', 'w') as f:
+            f.write(f'CHAVE_API_DEMO = \'{chave_api}\'\n')
 
 import modulos.coingecko_api as cgapi