diff --git a/docker/backend/src/backend/api/schema/user.cr b/docker/backend/src/backend/api/schema/user.cr
index fe78d5c..9561f17 100644
--- a/docker/backend/src/backend/api/schema/user.cr
+++ b/docker/backend/src/backend/api/schema/user.cr
@@ -26,14 +26,14 @@ module Backend
 
         @[GraphQL::Field]
         # User's first name
-        def firstname : String
-          find!.firstname
+        def first_name : String
+          find!.first_name
         end
 
         @[GraphQL::Field]
         # User's last name
-        def lastname : String
-          find!.lastname
+        def last_name : String
+          find!.last_name
         end
 
         @[GraphQL::Field]
diff --git a/docker/backend/src/backend/db/user.cr b/docker/backend/src/backend/db/user.cr
index d057b36..d252873 100644
--- a/docker/backend/src/backend/db/user.cr
+++ b/docker/backend/src/backend/db/user.cr
@@ -36,12 +36,12 @@ module Backend
       column admin : Bool = false
 
       # User's first name
-      def firstname : String
+      def first_name : String
         Ldap.user(Ldap.uid(@username.not_nil!)).first["givenName"].first
       end
 
       # User's last name
-      def lastname : String
+      def last_name : String
         Ldap.user(Ldap.uid(@username.not_nil!)).first["sn"].first
       end
 
diff --git a/docker/backend/src/backend/mailers/templates/teacher_registration_mailer.txt.ecr b/docker/backend/src/backend/mailers/templates/teacher_registration_mailer.txt.ecr
index aee9b2f..38f0307 100644
--- a/docker/backend/src/backend/mailers/templates/teacher_registration_mailer.txt.ecr
+++ b/docker/backend/src/backend/mailers/templates/teacher_registration_mailer.txt.ecr
@@ -1,4 +1,4 @@
-Hey, <%= user.firstname %>!
+Hey, <%= user.first_name %>!
 
 Du wurdest erfolgreich als Lehrer registriert.
 Initialisiere deinen Account, indem du auf den folgenden Link klickst und deine Daten eingibst: