diff --git a/dlibrary/dlibrary.py b/dlibrary/dlibrary.py
index 386230b..cb6cb0e 100755
--- a/dlibrary/dlibrary.py
+++ b/dlibrary/dlibrary.py
@@ -531,6 +531,7 @@ class Collator:
                 return split_attempt
 
         if all(src.is_file() and is_image(src) for src in srcs):
+            debug('Attempting to detect ordering for image files')
             ordering = complete_prefix_number_ordering(srcs)
             if not ordering and self.args.sort:
                 ordering = srcs.copy()
@@ -542,6 +543,11 @@ class Collator:
             else:
                 return None
 
+        debug('Unable to collate available file types:')
+        debug(f'Images: {[src for src in srcs if src.is_file() and is_image(src)]}')
+        debug(f'PDFs: {[src for src in srcs if src.is_file() and is_pdf(src)]}')
+        debug(f'Directories: {[src for src in srcs if src.is_dir()]}')
+        debug(f'Unknown files: {[src for src in srcs if src.is_file() and not is_image(src) and not is_pdf(src)]}')
         return None
 
     def link_pdf(self, src):
@@ -590,6 +596,8 @@ class Collator:
         if sum(1 for l in [early_srcs, middle_srcs, late_srcs] if l) <= 1:
             return False
 
+        debug(f'Splitting sources based on regex: {[early_srcs, middle_srcs, late_srcs]}')
+
         early_page_collation = self.collate_from_paths(early_srcs)
         if early_page_collation is None:
             return None
@@ -671,6 +679,7 @@ class Collator:
         if not all(any(lang.search(nname(src)) for lang in LANGUAGE_REGEXES.values()) for src in srcs):
             return False
 
+        debug('Detected multiple language options, selecting preferred language')
         srcs_matching_language = [src for src in srcs if LANGUAGE_REGEXES[self.args.locale].search(nname(src))]
         if len(srcs_matching_language) == len(srcs) or len(srcs_matching_language) == 0:
             return False