diff --git a/m4/mydns.m4 b/m4/mydns.m4
index a2e39c2..c174a18 100644
--- a/m4/mydns.m4
+++ b/m4/mydns.m4
@@ -446,7 +446,7 @@ AC_DEFUN([AC_ENABLE_STATUS],
 ##
 AC_DEFUN([AC_LIB_Z],
 	[
-		ac_zlib_dirs="/lib /usr/lib /usr/local/lib"
+		ac_zlib_dirs="/lib /usr/lib /usr/lib64 /usr/local/lib"
 		AC_ARG_WITH(zlib,
 			AC_HELP_STRING([--with-zlib=DIR], [look for the zlib compression library in DIR]),
 			ac_zlib_dirs="$withval $ac_zlib_dirs")
@@ -476,7 +476,7 @@ AC_DEFUN([AC_LIB_Z],
 ##
 AC_DEFUN([AC_LIB_Z_STATIC],
         [
-                ac_zlib_static_dirs="/lib /usr/lib /usr/local/lib"
+                ac_zlib_static_dirs="/lib /usr/lib /usr/lib64 /usr/local/lib"
                 AC_ARG_WITH(zlib_static,
                         AC_HELP_STRING([--with-zlib-static=DIR], [look for the static zlib compression library in DIR]),
                         ac_zlib_static_dirs="$withval $ac_zlib_static_dirs")
@@ -607,7 +607,7 @@ AC_DEFUN([AC_CHECK_MYSQL],
 ##
 AC_DEFUN([AC_LIB_PQ],
 	[
-		ac_mydns_lib_dirs="/usr/local/pgsql/lib /lib /usr/lib /usr/local/lib"
+		ac_mydns_lib_dirs="/lib /usr/lib /usr/lib64 /usr/local/lib /usr/local/pgsql/lib"
 		AC_ARG_WITH(pgsql-lib,
 			AC_HELP_STRING([--with-pgsql-lib=DIR],
 								[look for the PostgreSQL client library in DIR]),
@@ -635,8 +635,7 @@ AC_DEFUN([AC_LIB_PQ],
 ##
 AC_DEFUN([AC_HEADER_PQ],
 	[
-		ac_mydns_header_dirs="/usr/local/pgsql/include /usr/include/postgresql \
-									 /usr/include /usr/local/include"
+		ac_mydns_header_dirs="/usr/include/postgresql /usr/include /usr/local/include /usr/local/pgsql/include"
 		ac_mydns_header_found=no, ac_mydns_header_ok=no
 		AC_ARG_WITH(pgsql-include,
 			AC_HELP_STRING([--with-pgsql-include=DIR],