diff --git a/lib/graphql/resolvers/participant.ex b/lib/graphql/resolvers/participant.ex
index e752c0a5..f488e88c 100644
--- a/lib/graphql/resolvers/participant.ex
+++ b/lib/graphql/resolvers/participant.ex
@@ -282,6 +282,9 @@ defmodule Mobilizon.GraphQL.Resolvers.Participant do
         {:error,
          dgettext("errors", "Participation is confirmed but not approved yet by an organizer")}
 
+      {:has_participant, %Participant{role: :participant}} ->
+        {:error, dgettext("errors", "Participation is already confirmed")}
+
       {:has_participant, nil} ->
         {:error, dgettext("errors", "This token is invalid")}
 
diff --git a/test/graphql/resolvers/participant_test.exs b/test/graphql/resolvers/participant_test.exs
index bd431f14..8c8201d8 100644
--- a/test/graphql/resolvers/participant_test.exs
+++ b/test/graphql/resolvers/participant_test.exs
@@ -1136,6 +1136,15 @@ defmodule Mobilizon.GraphQL.Resolvers.ParticipantTest do
       assert %Participant{role: :participant} =
                event.id |> Events.list_participants_for_event() |> Map.get(:elements) |> hd()
 
+      res =
+        conn
+        |> AbsintheHelpers.graphql_query(
+          query: @confirmation_mutation,
+          variables: %{confirmationToken: confirmation_token}
+        )
+
+      assert hd(res["errors"])["message"] == "Participation is already confirmed"
+
       assert_email_sent(to: @email)
     end