diff --git a/help/help_diff.sh b/help/help_diff.sh
index 9d0da9258c..2096fa7709 100755
--- a/help/help_diff.sh
+++ b/help/help_diff.sh
@@ -1,19 +1,26 @@
 #!/bin/sh
 
-# This script compares a translated help file to the master file and prints
-# out any missing messages.  Needs the language code as parameter ($1).
+# This script walks through the master (stdin) help/message file, and
+# prints (stdout) only those messages which are missing from the help
+# file given as parameter ($1).
 #
-# Example: help_diff.sh hu
+# Example: help_diff.sh help_mp-hu.h < help_mp-en.h > missing.h
 
-exec < help_mp-en.h
+curr=""
 
-while read line; do
+while read -r line; do
 	if echo "$line" | grep '^#define' > /dev/null 2>&1; then
 		curr=`echo "$line" | cut -d ' ' -f 2`
-		if grep "^#define $curr" help_mp-$1.h > /dev/null 2>&1; then
-			true
-		else
-			echo "$line"
+		if grep "^#define $curr" $1 > /dev/null 2>&1; then
+			curr=""
+		fi
+	else
+		if [ -z "$line" ]; then
+			curr=""
 		fi
 	fi
+
+	if [ -n "$curr" ]; then
+		echo "$line"
+	fi
 done