diff --git a/src/gui/client/main-window.lisp b/src/gui/client/main-window.lisp
index 6ac76eb..356496a 100644
--- a/src/gui/client/main-window.lisp
+++ b/src/gui/client/main-window.lisp
@@ -476,7 +476,7 @@
                            (scale-jpeg main-window file-path))
                           ((member mime-type
                                    '("image/x-tga" "image/x-targa")
-                                   #'string=)
+                                   :test #'string=)
                            (scale-targa main-window file-path))
                           ((string= mime-type +mime-type-png+)
                            (scale-png main-window file-path))