diff --git a/org-clock-waybar.el b/org-clock-waybar.el
index 88d27d8..5064001 100644
--- a/org-clock-waybar.el
+++ b/org-clock-waybar.el
@@ -148,20 +148,20 @@ When nil, the percentage text will be an empty string."
 The output is in JSON format constructed in a way so Waybar can process it.
 If there is no clocked in task, alt becomes empty and text will be set to the
 value of `org-clock-waybar-not-clocked-in-text'."
-  (let* ((text-func (or 'org-clock-waybar-text-function
-                         'org-clock-waybar-get-task-title))
+  (let* ((text-func (or (and (fboundp ('org-clock-waybar-text-function)))
+                         #'org-clock-waybar-get-task-title))
          (text (funcall text-func))
-         (alt-func (or 'org-clock-waybar-alt-function
-                       'org-clock-waybar-get-task-category))
+         (alt-func (or (and (fboundp ('org-clock-waybar-alt-function)))
+                       #'org-clock-waybar-get-task-category))
          (alt (funcall alt-func))
-         (tooltip-func (or 'org-clock-waybar-tooltip-function
-                           'org-clock-waybar-get-tooltip))
+         (tooltip-func (or (and (fboundp ('org-clock-waybar-tooltip-function)))
+                           #'org-clock-waybar-get-tooltip))
          (tooltip (funcall tooltip-func))
-         (class-func (or 'org-clock-waybar-class-function
-                         'org-clock-waybar-get-tags))
+         (class-func (or (and (fboundp ('org-clock-waybar-class-function)))
+                         #'org-clock-waybar-get-tags))
          (class (funcall class-func))
-         (percentage (when (fboundp 'org-clock-waybar-percentage-function)
-                       (funcall 'org-clock-waybar-percentage-function)))
+         (percentage (when (fboundp #'org-clock-waybar-percentage-function)
+                       (funcall #'org-clock-waybar-percentage-function)))
          (output (json-new-object)))
     (or (null title)
         (stringp title)