diff --git a/storage/channel.go b/storage/channel.go
index 3aa23e33..e358b916 100644
--- a/storage/channel.go
+++ b/storage/channel.go
@@ -51,6 +51,13 @@ func (c *ChannelStore) AddUser(user, server, channel string) {
 	}
 
 	if users, ok := c.users[server][channel]; ok {
+		for _, u := range users {
+			if u == user {
+				c.userLock.Unlock()
+				return
+			}
+		}
+
 		c.users[server][channel] = append(users, user)
 	} else {
 		c.users[server][channel] = []string{user}
diff --git a/storage/channel_test.go b/storage/channel_test.go
index add3107d..4002ff92 100644
--- a/storage/channel_test.go
+++ b/storage/channel_test.go
@@ -16,6 +16,8 @@ func TestGetSetUsers(t *testing.T) {
 func TestAddRemoveUser(t *testing.T) {
 	channelStore := NewChannelStore()
 	channelStore.AddUser("user", "srv", "#chan")
+	channelStore.AddUser("user", "srv", "#chan")
+	assert.Len(t, channelStore.GetUsers("srv", "#chan"), 1)
 	channelStore.AddUser("user2", "srv", "#chan")
 	assert.Equal(t, []string{"user", "user2"}, channelStore.GetUsers("srv", "#chan"))
 	channelStore.RemoveUser("user", "srv", "#chan")