diff --git a/src/ext/popup-message.lisp b/src/ext/popup-message.lisp
index 38e29043c..d09bc1b5c 100644
--- a/src/ext/popup-message.lisp
+++ b/src/ext/popup-message.lisp
@@ -33,6 +33,10 @@
                      :buffer buffer
                      :width width
                      :height height
+                     ;; NOTE: Block mouse clicks on popup windows to prevent them from gaining focus.
+                     ;; If a popup window gains focus, it becomes the only active window in the window-tree,
+                     ;; which prevents Lem from being able to close it.
+                     ;; Mouse scrolling remains enabled since popup windows are used for displaying text content.                     :clickable nil
                      :style style)))
         (buffer-start (window-view-point window))
         (window-see window)
diff --git a/src/ext/popup-window.lisp b/src/ext/popup-window.lisp
index 6789c055b..f910c9979 100644
--- a/src/ext/popup-window.lisp
+++ b/src/ext/popup-window.lisp
@@ -308,6 +308,7 @@
                                (buffer (alexandria:required-argument :buffer))
                                (width (alexandria:required-argument :width))
                                (height (alexandria:required-argument :height))
+                               (clickable t)
                                style)
   (let* ((style (ensure-style style))
          (border-size (if (style-use-border style) +border-size+ 0))
@@ -335,6 +336,7 @@
                      :border-shape (style-shape style)
                      :background-color (style-background-color style)
                      :cursor-invisible (style-cursor-invisible style)
+                     :clickable clickable
                      :style style))))
 
 (defun update-popup-window (&key (source-window (alexandria:required-argument :source-window))
diff --git a/src/mouse.lisp b/src/mouse.lisp
index 162722439..2af09a253 100644
--- a/src/mouse.lisp
+++ b/src/mouse.lisp
@@ -178,7 +178,8 @@
            (focus-window-position (current-frame)
                                   (mouse-event-x mouse-event)
                                   (mouse-event-y mouse-event))
-         (when window
+         (when (and window
+                    (window-clickable window))
            (handle-mouse-button-down (window-buffer window)
                                      mouse-event
                                      :window window
diff --git a/src/window/window.lisp b/src/window/window.lisp
index 45e5627ae..c5d500066 100644
--- a/src/window/window.lisp
+++ b/src/window/window.lisp
@@ -105,6 +105,10 @@
    (deleted
     :initform nil
     :accessor window-deleted-p)
+   (clickable
+    :initarg :clickable
+    :initform t
+    :reader window-clickable)
    (parameters
     :initform nil
     :accessor window-parameters)))