Started with new style completions

zsh/completions/_dt

@@ -0,0 +1,11 @@
+#compdef dt
+
+function _dt {
+    local -a cmdlist
+    for line in $(tmux list-sessions -F '#S'); do
+        cmdlist=($cmdlist "${line}")
+    done
+    _describe 'Tmux Sessions' cmdlist
+}
+
+_dt "$@"

zsh/zshrc

@@ -61,11 +61,6 @@ function dt() {
     tmux -2 new-session -A -s $session_name
 } 
 
-function _dt_completion {
-    reply=($(tmux list-sessions -F '#S'))
-}
-compctl -K _dt_completion dt
-
 function send-to-pane() {
     tmux pipe-pane -I -t $1 "$2"
 }