diff --git a/util/configure b/util/configure
index 341a12f..a61ea3f 100755
--- a/util/configure
+++ b/util/configure
@@ -420,7 +420,7 @@ _END_
     my $opts_line = '';
 
     if ($opts->{debug}) {
-        unshift @ngx_cc_opts, '-O0';
+        #unshift @ngx_cc_opts, '-O0';
         $opts_line .= " \\\n  --with-debug";
 
     } else {
@@ -653,7 +653,7 @@ _EOC_
             if ($on_solaris) {
                 $extra_opts .= " INSTALL=$root_dir/build/install";
                 if ($opts->{debug}) {
-                    $extra_opts .= " CFLAGS=\"-g -O0 -Wall -pedantic -DMISSING_ISINF\"";
+                    $extra_opts .= " CFLAGS=\"-g -O -Wall -pedantic -DMISSING_ISINF\"";
 
                 } else {
                     $extra_opts .= " CFLAGS=\"-g -O3 -Wall -pedantic -DMISSING_ISINF\"";
@@ -661,7 +661,7 @@ _EOC_
 
             } else {
                 if ($opts->{debug}) {
-                    $extra_opts .= " CFLAGS=\"-g -O0 -Wall -pedantic\"";
+                    $extra_opts .= " CFLAGS=\"-g -O -Wall -pedantic\"";
                 }
             }
 
@@ -702,13 +702,13 @@ _EOC_
             if ($on_solaris) {
                 $extra_opts .= " INSTALL=$root_dir/build/install";
                 if ($opts->{debug}) {
-                    $extra_opts .= " CFLAGS=\"-g -O0 -Wall\"";
+                    $extra_opts .= " CFLAGS=\"-g -O -Wall\"";
 
                 }
 
             } else {
                 if ($opts->{debug}) {
-                    $extra_opts .= " CFLAGS=\"-g -O0 -Wall\"";
+                    $extra_opts .= " CFLAGS=\"-g -O -Wall\"";
                 }
             }
 
@@ -749,13 +749,13 @@ _EOC_
             if ($on_solaris) {
                 $extra_opts .= " INSTALL=$root_dir/build/install";
                 if ($opts->{debug}) {
-                    $extra_opts .= " CFLAGS=\"-g -O0 -Wall\"";
+                    $extra_opts .= " CFLAGS=\"-g -O -Wall\"";
 
                 }
 
             } else {
                 if ($opts->{debug}) {
-                    $extra_opts .= " CFLAGS=\"-g -O0 -Wall\"";
+                    $extra_opts .= " CFLAGS=\"-g -O -Wall\"";
                 }
             }