Index: zgrep.in
===================================================================
--- zgrep.in.orig	2012-01-01 09:53:58.000000000 +0100
+++ zgrep.in	2012-10-16 13:22:26.304769138 +0200
@@ -174,10 +174,18 @@ res=0
 
 for i
 do
+  case $i in
+    *.bz2)
+      uncompress=bzip2
+      ;;
+    *)
+      uncompress=gzip
+      ;;
+  esac
   # Fail if gzip or grep (or sed) fails.
   gzip_status=$(
     exec 5>&1
-    (gzip -cdfq -- "$i" 5>&-; echo $? >&5) 3>&- |
+    ($uncompress -cdfq -- "$i" 5>&-; echo $? >&5) 3>&- |
     if test $files_with_matches -eq 1; then
       eval "$grep" >/dev/null && { printf '%s\n' "$i" || exit 2; }
     elif test $files_without_matches -eq 1; then