diff --git a/src/calibre/ebooks/metadata/docx.py b/src/calibre/ebooks/metadata/docx.py
index 05bf6d9ffc..1eaac21c5b 100644
--- a/src/calibre/ebooks/metadata/docx.py
+++ b/src/calibre/ebooks/metadata/docx.py
@@ -29,6 +29,8 @@ def get_cover(docx):
                 fmt, width, height = identify(bytes(raw))
             except Exception:
                 continue
+            if width < 0 or height < 0:
+                continue
             if 0.8 <= height/width <= 1.8 and height*width >= 160000:
                 return (fmt, raw)
 
diff --git a/src/calibre/ebooks/metadata/odt.py b/src/calibre/ebooks/metadata/odt.py
index 31129f5281..695db0c258 100644
--- a/src/calibre/ebooks/metadata/odt.py
+++ b/src/calibre/ebooks/metadata/odt.py
@@ -259,7 +259,7 @@ def read_cover(stream, zin, mi, opfmeta, extract_cover):
             if not cover_data:
                 raw = zin.read(cover_href)
                 try:
-                    fmt, width, height = identify(bytes(raw))
+                    fmt = identify(bytes(raw))[0]
                 except Exception:
                     pass
                 else: