diff --git a/src/calibre/ebooks/metadata/pdf.py b/src/calibre/ebooks/metadata/pdf.py
index 76c88aece9..c220cf74fc 100644
--- a/src/calibre/ebooks/metadata/pdf.py
+++ b/src/calibre/ebooks/metadata/pdf.py
@@ -95,7 +95,7 @@ def get_metadata(stream, cover=True):
             raw = f.read().strip()
             if raw:
                 prints(raw)
-        if not info:
+        if info is None:
             raise ValueError('Could not read info dict from PDF')
         covpath = os.path.join(pdfpath, 'cover.jpg')
         cdata = None
@@ -103,7 +103,7 @@ def get_metadata(stream, cover=True):
             with open(covpath, 'rb') as f:
                 cdata = f.read()
 
-    title = info.get('Title', None)
+    title = info.get('Title', None) or _('Unknown')
     au = info.get('Author', None)
     if au is None:
         au = [_('Unknown')]