diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 1f2a9d1d8d94f..b1e2610426cb9 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -5195,7 +5195,7 @@ function printCommonFooter($zone='private')
 		print 'window.console && console.log("';
 		if (! empty($conf->global->MEMCACHED_SERVER)) print 'MEMCACHED_SERVER='.$conf->global->MEMCACHED_SERVER.' - ';
 		print 'MAIN_OPTIMIZE_SPEED='.(isset($conf->global->MAIN_OPTIMIZE_SPEED)?$conf->global->MAIN_OPTIMIZE_SPEED:'off');
-		if ($micro_start_time)
+		if (! empty($micro_start_time))   // Works only if MAIN_SHOW_TUNING_INFO is defined at $_SERVER level. Not in global variable.
 		{
 			$micro_end_time = microtime(true);
 			print ' - Build time: '.ceil(1000*($micro_end_time-$micro_start_time)).' ms';