diff --git a/auto/lib/perl/conf b/auto/lib/perl/conf
index 52c7084e9..5ce6c91e6 100644
--- a/auto/lib/perl/conf
+++ b/auto/lib/perl/conf
@@ -12,7 +12,7 @@ NGX_PERL_VER=`$NGX_PERL -v 2>&1 | grep '^This is perl' 2>&1 \
 if test -n "$NGX_PERL_VER"; then
     echo " + perl version: $NGX_PERL_VER"
 
-    if [ "`echo 'use 5.006001; print "OK"' | $NGX_PERL 2>&1`" != OK ]; then
+    if [ "`$NGX_PERL -e 'use 5.006001; print "OK"'`" != "OK" ]; then
         echo
         echo "$0: error: perl 5.6.1 or higher is required"
         echo
@@ -20,6 +20,14 @@ if test -n "$NGX_PERL_VER"; then
         exit 1;
     fi
 
+    if [ "`$NGX_PERL -MExtUtils::Embed -e 'print "OK"'`" != "OK" ]; then
+        echo
+        echo "$0: error: perl module ExtUtils::Embed is required"
+        echo
+
+        exit 1;
+    fi
+
     NGX_PERL_CFLAGS="$CFLAGS `$NGX_PERL -MExtUtils::Embed -e ccopts`"
     NGX_PM_CFLAGS=`$NGX_PERL -MExtUtils::Embed -e ccopts`
 
diff --git a/auto/options b/auto/options
index 11f23c6d6..6c3a4db97 100644
--- a/auto/options
+++ b/auto/options
@@ -385,6 +385,10 @@ cat << END
   --without-http_browser_module      disable ngx_http_browser_module
   --without-http_upstream_ip_hash_module
                                      disable ngx_http_upstream_ip_hash_module
+  --without-http_upstream_least_conn_module
+                                     disable ngx_http_upstream_least_conn_module
+  --without-http_upstream_keepalive_module
+                                     disable ngx_http_upstream_keepalive_module
 
   --with-http_perl_module            enable ngx_http_perl_module
   --with-perl_modules_path=PATH      set Perl modules path