diff --git a/tools/build/build.py b/tools/build/build.py
index 57974854..913f23c8 100755
--- a/tools/build/build.py
+++ b/tools/build/build.py
@@ -196,14 +196,14 @@ def build_oxjs(downloads=False, geo=False):
             # locale json files are loaded lazily
             # Ox.UI.css imports all other css files
             # svgs are loaded as URLs or dataURLs
-            # browser images appear before load
+            # Ox.UI PNGs are loaded on demand
             if path != root and not '_' in path and not filename[0] in '._' \
                     and not filename.endswith('~') \
                     and not 'jquery' in filename \
                     and not 'locale' in filename \
                     and not filename.endswith('theme.css') \
                     and not filename.endswith('.svg') \
-                    and not filename.startswith('browser'):
+                    and not 'Ox.UI/png' in path:
                 ui_files['dev'].append(os.path.join(path.replace(source_path, ''), filename))
                 if not '/js/' in path:
                     ui_files['build'].append(os.path.join(path.replace(source_path, ''), filename))