diff --git a/tools/skqp/download_model b/tools/skqp/download_model
index c18ebfa..209f550 100755
--- a/tools/skqp/download_model
+++ b/tools/skqp/download_model
@@ -43,11 +43,14 @@
     return path
 
 def main():
-    os.chdir(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir,
-                         'platform_tools', 'android', 'apps', 'skqp', 'src',
-                         'main', 'assets'))
+    target_dir = os.path.join('platform_tools', 'android', 'apps', 'skqp', 'src', 'main', 'assets')
+    os.chdir(os.path.join(os.path.dirname(__file__), os.pardir, os.pardir, target_dir))
+    checksum_path = 'files.checksum'
+    if not os.path.isfile(checksum_path):
+        sys.stderr.write('Error: "%s" is missing.\n' % os.path.join(target_dir, checksum_path))
+        sys.exit(1)
     file_list_file = tmp('files_')
-    with open('files.checksum', 'r') as f:
+    with open(checksum_path, 'r') as f:
         md5 = f.read().strip()
         assert(len(md5) == 32)
         download(md5, file_list_file)