--- lib/gettext/tools/pomessage.rb.debug	2009-11-14 11:45:04.000000000 +0900
+++ lib/gettext/tools/pomessage.rb	2009-11-18 04:59:36.000000000 +0900
@@ -60,7 +60,7 @@
     # Checks if the other translation target is mergeable with
     # the current one. Relevant are msgid and translation context (msgctxt).
     def ==(other)
-      other.msgid == self.msgid && other.msgctxt == self.msgctxt
+      other && other.msgid == self.msgid && other.msgctxt == self.msgctxt
     end
 
     # Merges two translation targets with the same msgid and returns the merged
--- lib/gettext/tools/rgettext.rb.debug	2009-11-14 11:45:04.000000000 +0900
+++ lib/gettext/tools/rgettext.rb	2009-11-18 04:57:14.000000000 +0900
@@ -118,7 +118,7 @@
                 end
 
                 # Save the previous target.
-                existing = pomessages.find_index {|t| t == pomessage}
+                existing = pomessages.empty? ? nil : pomessages.index(pomessages.find {|t| t == pomessage})
                 if existing
                   pomessage = pomessages[existing].merge(pomessage)
                   pomessages[existing] = pomessage