diff --git a/src/prefs.js b/src/prefs.js
index abf1ffb..d0e1f92 100644
--- a/src/prefs.js
+++ b/src/prefs.js
@@ -455,8 +455,11 @@ const Preferences = class {
         this.settings.connect('changed::background-day', () => updateBackgroundsBackgroundsDayBackgroundButtonUri());
         backgroundsBackgroundsDayBackgroundButton.connect('update-preview', () => {
             const file = backgroundsBackgroundsDayBackgroundButton.get_preview_filename();
-            const pixbuf = GdkPixbuf.Pixbuf.new_from_file_at_size(file, 256, 256);
-            dayBackgroundPreview.set_from_pixbuf(pixbuf);
+            const allowedContentTypes = ['image/jpeg', 'image/png', 'image/tiff'];
+            if (allowedContentTypes.includes(Gio.content_type_guess(file, null)[0])) {
+                const pixbuf = GdkPixbuf.Pixbuf.new_from_file_at_size(file, 256, 256);
+                dayBackgroundPreview.set_from_pixbuf(pixbuf);
+            }
         });
         backgroundsBackgroundsDayBackgroundButton.connect('file-set', () => {
             this.settings.set_string('background-day', backgroundsBackgroundsDayBackgroundButton.get_uri());
@@ -471,8 +474,11 @@ const Preferences = class {
         this.settings.connect('changed::background-night', () => updateBackgroundsBackgroundsNightBackgroundButtonUri());
         backgroundsBackgroundsNightBackgroundButton.connect('update-preview', () => {
             const file = backgroundsBackgroundsNightBackgroundButton.get_preview_filename();
-            const pixbuf = GdkPixbuf.Pixbuf.new_from_file_at_size(file, 256, 256);
-            nightBackgroundPreview.set_from_pixbuf(pixbuf);
+            const allowedContentTypes = ['image/jpeg', 'image/png', 'image/tiff'];
+            if (allowedContentTypes.includes(Gio.content_type_guess(file, null)[0])) {
+                const pixbuf = GdkPixbuf.Pixbuf.new_from_file_at_size(file, 256, 256);
+                nightBackgroundPreview.set_from_pixbuf(pixbuf);
+            }
         });
         backgroundsBackgroundsNightBackgroundButton.connect('file-set', () => {
             this.settings.set_string('background-night', backgroundsBackgroundsNightBackgroundButton.get_uri());
diff --git a/src/prefs.ui b/src/prefs.ui
index 301c296..4fd5005 100644
--- a/src/prefs.ui
+++ b/src/prefs.ui
@@ -20,7 +20,7 @@
     <property name="visible">True</property>
     <property name="can_focus">False</property>
     <property name="pixel_size">256</property>
-    <property name="icon_name">image-loading</property>
+    <property name="icon_name">image-missing</property>
     <property name="icon_size">0</property>
   </object>
   <object class="GtkDialog" id="ondemand_keyboard_shortcut_dialog">