diff --git a/app/src/main/java/fr/gouv/etalab/mastodon/activities/LoginActivity.java b/app/src/main/java/fr/gouv/etalab/mastodon/activities/LoginActivity.java
index e20d7fd74..35f7596b5 100644
--- a/app/src/main/java/fr/gouv/etalab/mastodon/activities/LoginActivity.java
+++ b/app/src/main/java/fr/gouv/etalab/mastodon/activities/LoginActivity.java
@@ -21,6 +21,7 @@ import android.graphics.Paint;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
+import android.util.Patterns;
 import android.view.Menu;
 import android.view.MenuItem;
 import android.view.View;
@@ -103,7 +104,12 @@ public class LoginActivity extends AppCompatActivity {
                 connectionButton.setEnabled(false);
                 login_two_step.setVisibility(View.INVISIBLE);
                 if (!hasFocus) {
-                    retrievesClientId();
+                    if( Patterns.WEB_URL.matcher(login_instance.getText().toString().trim()).matches() ){
+                        retrievesClientId();
+                    }else {
+                        Toast.makeText(getApplicationContext(), R.string.toast_error_instance, Toast.LENGTH_LONG).show();
+                    }
+
                 }
             }
         });
diff --git a/app/src/main/res/layout/activity_login.xml b/app/src/main/res/layout/activity_login.xml
index 6bd70a493..79dcb5a08 100644
--- a/app/src/main/res/layout/activity_login.xml
+++ b/app/src/main/res/layout/activity_login.xml
@@ -45,7 +45,7 @@
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:inputType="textWebEmailAddress"
-                android:hint="@string/instance"
+                android:hint="@string/instance_example"
                 />
             <EditText
                 android:id="@+id/login_uid"
diff --git a/app/src/main/res/values-fr/strings.xml b/app/src/main/res/values-fr/strings.xml
index 19e0a8fe9..c2c782cf5 100644
--- a/app/src/main/res/values-fr/strings.xml
+++ b/app/src/main/res/values-fr/strings.xml
@@ -33,6 +33,7 @@
     <string name="other_instance">Autre instance que mastodon.etalab.gouv.fr ?</string>
     <string name="no_result">Aucun résultat !</string>
     <string name="instance">Instance</string>
+    <string name="instance_example">Instance : mastodon.social</string>
     <string name="toast_account_changed">Utilisation du compte %1$s</string>
     <string name="add_account">Ajouter un compte</string>
     <string name="clipboard">Le contenu du pouet a été copié dans le presse-papier</string>
@@ -228,6 +229,7 @@
     <string name="toast_unstatus">Le pouet a été supprimé !</string>
     <string name="toast_error">Oups ! Une erreur s\'est produite !</string>
     <string name="toast_code_error">Une erreur s\'est produite ! L\'instance n\'a retourné aucun code d\authorisation !</string>
+    <string name="toast_error_instance">Le nom de l\'instance ne semble pas être valide !</string>
     <string name="toast_error_loading_account">Une erreur s\'est produite en chargeant le compte !</string>
     <string name="toast_error_search">Une erreur s\'est produite lors de la recherche !</string>
     <string name="toast_error_login">Impossible de vous connecter !</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 2fcdef145..c6600597c 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -34,6 +34,7 @@
     <string name="other_instance">Other instance than mastodon.etalab.gouv.fr?</string>
     <string name="no_result">No results!</string>
     <string name="instance">Instance</string>
+    <string name="instance_example">Instance: mastodon.social</string>
     <string name="toast_account_changed">Now works with the account %1$s</string>
     <string name="add_account">Add an account</string>
     <string name="clipboard">The content of the toot has been copied to the clipboard</string>
@@ -233,6 +234,7 @@
     <string name="toast_unstatus">The toot was deleted!</string>
     <string name="toast_error">Oops ! An error occurred!</string>
     <string name="toast_code_error">An error occurred! The instance did not return an authorisation code!</string>
+    <string name="toast_error_instance">The instance domain does not seem to be valide!</string>
     <string name="toast_error_loading_account">An error occurred while switching between accounts!</string>
     <string name="toast_error_search">An error occurred while searching!</string>
     <string name="toast_error_login">Can not log in!</string>