diff --git a/package/rene/exim/exim.conf b/package/rene/exim/exim.conf
index 56329e777..b0ed67bc5 100644
--- a/package/rene/exim/exim.conf
+++ b/package/rene/exim/exim.conf
@@ -25,6 +25,8 @@ exim_main()
   echo "merging exiscan ..."
   bunzip2 -c $archdir/exiscan-${exiscan_version}.patch.bz2 | patch -p1
 
+  [ "${prefix#opt/}" == "$prefix" ] && sysconfdir="$sysconfdir/exim"
+
   var_append makeopt "BIN_DIRECTORY=$bindir \
                       CONFIGURE_FILE=$sysconfdir/configure \
                       EXIM_USER=10 EXIM_GROUP=10 AUTH_CRAM_MD5=yes \