diff --git a/src/calibre/ebooks/metadata/book/base.py b/src/calibre/ebooks/metadata/book/base.py
index 1efa47521b..2d14faf4ff 100644
--- a/src/calibre/ebooks/metadata/book/base.py
+++ b/src/calibre/ebooks/metadata/book/base.py
@@ -26,8 +26,8 @@ def human_readable(size, precision=2):
     """ Convert a size in bytes into megabytes """
     ans = size/(1024*1024)
     if ans < 0.1:
-        return '<0.1MB'
-    return ('%.'+str(precision)+'f'+ 'MB') % ans
+        return '<0.1 MB'
+    return ('%.'+str(precision)+'f'+ ' MB') % ans
 
 
 NULL_VALUES = {