diff --git a/config/config.exs b/config/config.exs
index f1bd2df5a..c584ad18c 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -192,6 +192,7 @@ config :mobilizon, Mobilizon.Service.Formatter,
 config :tesla, adapter: Tesla.Adapter.Hackney
 
 config :phoenix, :format_encoders, json: Jason, "activity-json": Jason
+config :phoenix, :json_library, Jason
 config :phoenix, :filter_parameters, ["password", "token"]
 
 config :absinthe, schema: Mobilizon.GraphQL.Schema