diff --git a/eca-chat-context.el b/eca-chat-context.el
index 2f18c4c..98ca55b 100644
--- a/eca-chat-context.el
+++ b/eca-chat-context.el
@@ -488,7 +488,9 @@ DATA is the binary image data as a string."
     (seq-some (lambda (type)
                 (and (symbolp type)
                      (string-match-p "^image/" (symbol-name type))))
-              (if (vectorp targets) (append targets nil) targets))))
+              (cond ((vectorp targets) (append targets nil))
+                     ((symbolp targets) (list targets))
+                     (t targets)))))
 
 (defun eca-chat--yank-considering-image (orig-fun &rest args)
   "Around advice for paste commands to use `yank-media' for images.
diff --git a/test/eca-chat-context-test.el b/test/eca-chat-context-test.el
index c860b45..5a9d404 100644
--- a/test/eca-chat-context-test.el
+++ b/test/eca-chat-context-test.el
@@ -430,5 +430,31 @@
             (set-buffer-modified-p nil))
           (kill-buffer buf))))))
 
+(describe "eca-chat--clipboard-image-p"
+  (before-each
+    (spy-on 'display-graphic-p :and-return-value t))
+
+  (it "returns non-nil when TARGETS contains an image type"
+    (spy-on 'gui-get-selection
+            :and-return-value (vector 'TARGETS 'UTF8_STRING 'image/png))
+    (expect (eca-chat--clipboard-image-p) :to-be-truthy))
+
+  (it "returns nil when TARGETS is a vector without an image type"
+    (spy-on 'gui-get-selection
+            :and-return-value (vector 'TARGETS 'UTF8_STRING 'STRING))
+    (expect (eca-chat--clipboard-image-p) :to-be nil))
+
+  (it "returns nil without erroring when TARGETS is a bare symbol"
+    ;; Some X11 clients (e.g. st) only advertise a single selection
+    ;; target, in which case `gui-get-selection' returns a bare
+    ;; symbol instead of a vector/list of targets.
+    (spy-on 'gui-get-selection :and-return-value 'UTF8_STRING)
+    (expect (eca-chat--clipboard-image-p) :to-be nil))
+
+  (it "returns non-nil when TARGETS is a list containing an image type (default pass-through)"
+    (spy-on 'gui-get-selection
+            :and-return-value (list 'TARGETS 'UTF8_STRING 'image/png))
+    (expect (eca-chat--clipboard-image-p) :to-be-truthy)))
+
 (provide 'eca-chat-context-test)
 ;;; eca-chat-context-test.el ends here