diff --git a/petitions/forms.py b/petitions/forms.py
index cdc73746ff140d20c972240c8cb32f55b0fb7e4f..7321a5178d4cf265d135995e3bc15234147d439c 100644
--- a/petitions/forms.py
+++ b/petitions/forms.py
@@ -12,20 +12,32 @@ class SignPetitionForm(forms.ModelForm):
 
     class Meta:
         model = PetitionSignatory
-        fields = ['petition', 'title', 'first_name', 'last_name',
+        fields = ['title', 'first_name', 'last_name',
                   'email', 'country_of_employment', 'affiliation']
-        widgets = {'petition': forms.HiddenInput()}
 
+    def __init__(self, *args, **kwargs):
+        self.petition = kwargs.pop('petition', False)
+        self.current_user = kwargs.pop('current_user', False)
+        super().__init__(*args, **kwargs)
 
     def clean_email(self):
         email = self.cleaned_data['email']
-        petition = self.cleaned_data['petition']
+        petition = self.petition
+        if not petition:
+            return email
+
         if self.instance.id:
             return email
 
-        if Contributor.objects.filter(user__email=email).exists():
-            self.add_error('email', ('This email address is associated to a Contributor; please '
-                                     'login to sign the petition'))
-        elif PetitionSignatory.objects.filter(petition=petition, email=email).exists():
+        if self.current_user.is_authenticated():
+            if self.current_user.email != email:
+                self.add_error('email', 'This email address is not associated to your account')
+        else:
+            if Contributor.objects.filter(user__email=email).exists():
+                self.add_error('email', ('This email address is associated to a Contributor; please '
+                                         'login to sign the petition'))
+        if PetitionSignatory.objects.filter(petition=petition, email=email).exists():
             self.add_error('email', ('This email address is already associated to a '
                                      'signature for this petition'))
+
+        return email
diff --git a/petitions/views.py b/petitions/views.py
index 56ead1eea6c32dc2bd0487b4f901d5f36629fabf..7caab2ca1571b95c1d31f420e1b8fb1763d6ac1c 100644
--- a/petitions/views.py
+++ b/petitions/views.py
@@ -29,7 +29,8 @@ def petition(request, slug):
             'affiliation': request.user.contributor.affiliation,
         }
 
-    form = SignPetitionForm(request.POST or None, initial=initial)
+    form = SignPetitionForm(request.POST or None, initial=initial, petition=petition,
+                            current_user=request.user)
     if form.is_valid():
         signature = form.save(commit=False)
         signature.petition = petition