diff --git a/epubfile.py b/epubfile.py
index 06d8f10..de6a4ba 100644
--- a/epubfile.py
+++ b/epubfile.py
@@ -1297,11 +1297,10 @@ def holdit_argparse(args):
 def merge(input_filepaths, output_filename, do_headerfile=False):
     book = Epub.new()
 
+    input_filepaths = [pathclass.Path(p) for pattern in input_filepaths for p in glob.glob(pattern)]
     index_length = len(str(len(input_filepaths)))
     rand_prefix = random_string(3, string.digits)
 
-    input_filepaths = [pathclass.Path(p) for pattern in input_filepaths for p in glob.glob(pattern)]
-
     for (index, input_filepath) in enumerate(input_filepaths):
         print(f'Merging {input_filepath.absolute_path}.')
         prefix = f'{rand_prefix}_{index:>0{index_length}}_{{}}'