diff --git a/README.md b/README.md
index 9de48e6..37e33ed 100644
--- a/README.md
+++ b/README.md
@@ -1547,7 +1547,8 @@ Get properties for a layer or all layers in a group.
   (setq tp-layer-groups nil)
   (define-tp layer1 () '(face bold))
   (define-tp layer2 () '(face italic))
-  (tp-define-layer-group 'my-group 'layer1 'layer2)
+  (define-tps my-group ()
+    'layer1 'layer2)
   (length (tp-group-props 'my-group)))
 ;; => 2
 ```
@@ -1579,7 +1580,8 @@ Remove layer or group definition.
   (setq tp-layer-alist nil)
   (setq tp-layer-groups nil)
   (define-tp l1 () '(face bold))
-  (tp-define-layer-group 'my-group 'l1)
+  (define-tps my-group ()
+    'l1)
   (tp-undefine-group 'my-group)
   (assoc 'my-group tp-layer-groups))
 ;; => nil
diff --git a/tp.el b/tp.el
index 5dd5bf1..6669b1c 100644
--- a/tp.el
+++ b/tp.el
@@ -2865,11 +2865,26 @@ Recursively expands any nested layer names in the returned plist."
 
 (defun tp-group-props (group-name &optional include-tp-name)
   "Return list of properties for all layers in GROUP-NAME.
-If INCLUDE-TP-NAME is non-nil, each layer's props will include tp-name."
-  (when-let ((layers (cdr (assoc group-name tp-layer-groups))))
-    (mapcar (lambda (layer)
-              (tp-layer-props layer include-tp-name))
-            layers)))
+If INCLUDE-TP-NAME is non-nil, each layer's props will include tp-name.
+Handles both old format (list of layer names) and new unified format
+from `define-tps` (parameterized groups store ARGLIST and BODY-FORM)."
+  (when-let ((entry (cdr (assoc group-name tp-layer-groups))))
+    ;; Check if it's the unified format from define-tps (ARGLIST BODY-FORM)
+    ;; Unified format: (ARGLIST BODY-FORM) where ARGLIST is a list of symbols or nil
+    ;; Old format: (layer1 layer2 ...) where each element is a symbol referring to a layer
+    (cond
+     ;; Unified parameterized format: (ARGLIST BODY-FORM) with non-nil ARGLIST
+     ((and (= (length entry) 2)
+           (listp (car entry))
+           (not (null (car entry)))
+           (cl-every #'symbolp (car entry)))
+      ;; Parameterized group - can't get props without argument
+      nil)
+     ;; Old format or non-parameterized define-tps: list of layer names
+     (t
+      (mapcar (lambda (layer)
+                (tp-layer-props layer include-tp-name))
+              entry)))))
 
 (defun tp--is-layer-name-p (sym)
   "Return non-nil if SYM is a defined layer, parameterized layer, or group name."