Index: wp-includes/pomo/mo.php
===================================================================
--- wp-includes/pomo/mo.php	(revision 19787)
+++ wp-includes/pomo/mo.php	(working copy)
@@ -154,7 +154,7 @@
 
 		// read originals' indices
 		$originals_lengths_length = $translations_lenghts_addr - $originals_lenghts_addr;
-		if ( $originals_lengths_length != $total * 8 )
+		if ( !$originals_lengths_length || $originals_lengths_length != $total * 8 )
 			return false;
 
 		$originals = $reader->read($originals_lengths_length);
@@ -163,7 +163,7 @@
 
 		// read translations' indices
 		$translations_lenghts_length = $hash_addr - $translations_lenghts_addr;
-		if ( $translations_lenghts_length != $total * 8 )
+		if ( !$translations_lenghts_length || $translations_lenghts_length != $total * 8 )
 			return false;
 
 		$translations = $reader->read($translations_lenghts_length);