diff --git a/app.py b/app.py
index fd46304..55244c9 100644
--- a/app.py
+++ b/app.py
@@ -111,8 +111,14 @@ def post_user():
     def error(msg):
         return index_tpl(alerts=[('error', msg, 'fadeOut')], str=i18n.str)
 
+    def username_validation(e):
+        regex = r'^\w+$'
+        return(bool(re.fullmatch(regex, e)))
+
     if len(form('username')) < 3:
         return error(i18n.msg[1])
+    elif not username_validation(form('username')):
+        return error(i18n.msg[6])
 
     if len(form('password')) < 1:
         return error(i18n.msg[2])
@@ -178,6 +184,8 @@ def post_signup():
         surname = form('surname').lower()
 
     email = form('email').lower()
+    if not email_validation(email):
+        return error(i18n.msg[14])
 
     if form('password') != form('confirm-password'):
         return error(i18n.msg[7])