diff --git a/htdocs/main.inc.php b/htdocs/main.inc.php
index 9515f7a858a..d2da3d94dec 100644
--- a/htdocs/main.inc.php
+++ b/htdocs/main.inc.php
@@ -916,7 +916,10 @@ function top_htmlhead($head, $title='', $disablejs=0, $disablehead=0, $arrayofjs
 		{
 			foreach($conf->css_modules as $cssfile)
 			{	// cssfile is an absolute path
-				print '<link rel="stylesheet" type="text/css" title="default" href="'.dol_buildpath($cssfile,1).'?lang='.$langs->defaultlang.'&theme='.$conf->theme.(GETPOST('optioncss')?'&optioncss='.GETPOST('optioncss'):'').'">'."\n";
+				print '<link rel="stylesheet" type="text/css" title="default" href="'.dol_buildpath($cssfile,1);
+                // We add params only if page is not static, because some web server setup does not return content type text/css if url has parameters and browser cache is not used.
+				if (!preg_match('/\.css$/i',$cssfile)) print '?lang='.$langs->defaultlang.'&theme='.$conf->theme.(GETPOST('optioncss')?'&optioncss='.GETPOST('optioncss'):'');
+				print '">'."\n";
 			}
 		}
 		// CSS forced by page in top_htmlhead call (relative url starting with /)
@@ -924,7 +927,10 @@ function top_htmlhead($head, $title='', $disablejs=0, $disablehead=0, $arrayofjs
 		{
 			foreach($arrayofcss as $cssfile)
 			{
-				print '<link rel="stylesheet" type="text/css" title="default" href="'.dol_buildpath($cssfile,1).'?lang='.$langs->defaultlang.'&theme='.$conf->theme.(GETPOST('optioncss')?'&optioncss='.GETPOST('optioncss'):'').'">'."\n";
+				print '<link rel="stylesheet" type="text/css" title="default" href="'.dol_buildpath($cssfile,1);
+                // We add params only if page is not static, because some web server setup does not return content type text/css if url has parameters and browser cache is not used.
+				if (!preg_match('/\.css$/i',$cssfile)) print '?lang='.$langs->defaultlang.'&theme='.$conf->theme.(GETPOST('optioncss')?'&optioncss='.GETPOST('optioncss'):'');
+				print '">'."\n";
 			}
 		}