diff --git a/.env_sample b/.env_sample
index 4acfc4528..7a5e06992 100644
--- a/.env_sample
+++ b/.env_sample
@@ -1,5 +1,6 @@
 SECRET_KEY=change-this-secret
 
+# Database
 DB_HOST=db
 DB_NAME=postgres
 DB_USERNAME=postgres
diff --git a/src/apps/profiles/forms.py b/src/apps/profiles/forms.py
index a959acb8d..c2b0b43cc 100644
--- a/src/apps/profiles/forms.py
+++ b/src/apps/profiles/forms.py
@@ -4,8 +4,22 @@
 
 
 class SignUpForm(UserCreationForm):
-    email = forms.EmailField(max_length=254, help_text='Required. Inform a valid email address.')
+
+    email = forms.EmailField(
+        max_length=254, help_text="Required. Inform a valid email address."
+    )
+
+    def clean_username(self):
+        data = self.cleaned_data["username"]
+        if not data.islower():
+            raise forms.ValidationError("Usernames should be in lowercase")
+        if not data.isalnum():
+            raise forms.ValidationError(
+                "Usernames should not contain special characters."
+            )
+        return data
 
     class Meta:
+
         model = User
-        fields = ('username', 'email', 'password1', 'password2', )
+        fields = ("username", "email", "password1", "password2")