diff --git a/camelot/lattice.py b/camelot/lattice.py
index da8941a..52501e2 100644
--- a/camelot/lattice.py
+++ b/camelot/lattice.py
@@ -212,7 +212,7 @@ class Lattice:
         if not ltchar:
             logging.warning("{0}: PDF has no text. It may be an image.".format(
                 os.path.basename(bname)))
-            return None
+            return {os.path.basename(bname): None}
 
         imagename = ''.join([bname, '.png'])
         gs_call = [
diff --git a/camelot/stream.py b/camelot/stream.py
index ddd0976..6550066 100644
--- a/camelot/stream.py
+++ b/camelot/stream.py
@@ -307,7 +307,7 @@ class Stream:
         if not lttextlh:
             logging.warning("{0}: PDF has no text. It may be an image.".format(
                 os.path.basename(bname)))
-            return None
+            return {os.path.basename(bname): None}
 
         if self.debug:
             self.debug_text = []