diff --git a/htdocs/core/class/html.form.class.php b/htdocs/core/class/html.form.class.php
index 5eaa7d5ede8..f48ce989a7a 100644
--- a/htdocs/core/class/html.form.class.php
+++ b/htdocs/core/class/html.form.class.php
@@ -2507,7 +2507,7 @@ class Form
 
 		$label = $objp->label;
 		if (!empty($objp->label_translated)) $label = $objp->label_translated;
-		if (!empty($filterkey) && $filterkey != '') $label = preg_replace('/('.preg_quote($filterkey).')/i', '<strong>$1</strong>', $label, 1);
+		if (!empty($filterkey) && $filterkey != '') $label = preg_replace('/('.preg_quote($filterkey, '/').')/i', '<strong>$1</strong>', $label, 1);
 
 		$outkey = $objp->rowid;
 		$outref = $objp->ref;
@@ -2579,7 +2579,7 @@ class Form
 		if ($outorigin && !empty($conf->global->PRODUCT_SHOW_ORIGIN_IN_COMBO)) $opt .= ' ('.getCountry($outorigin, 1).')';
 
 		$objRef = $objp->ref;
-		if (!empty($filterkey) && $filterkey != '') $objRef = preg_replace('/('.preg_quote($filterkey).')/i', '<strong>$1</strong>', $objRef, 1);
+		if (!empty($filterkey) && $filterkey != '') $objRef = preg_replace('/('.preg_quote($filterkey, '/').')/i', '<strong>$1</strong>', $objRef, 1);
 		$outval .= $objRef;
 		if ($outbarcode) $outval .= ' ('.$outbarcode.')';
 		$outval .= ' - '.dol_trunc($label, $maxlengtharticle);
@@ -2948,11 +2948,11 @@ class Form
                 }
 
 				$objRef = $objp->ref;
-				if ($filterkey && $filterkey != '') $objRef = preg_replace('/('.preg_quote($filterkey).')/i', '<strong>$1</strong>', $objRef, 1);
+				if ($filterkey && $filterkey != '') $objRef = preg_replace('/('.preg_quote($filterkey, '/').')/i', '<strong>$1</strong>', $objRef, 1);
 				$objRefFourn = $objp->ref_fourn;
-				if ($filterkey && $filterkey != '') $objRefFourn = preg_replace('/('.preg_quote($filterkey).')/i', '<strong>$1</strong>', $objRefFourn, 1);
+				if ($filterkey && $filterkey != '') $objRefFourn = preg_replace('/('.preg_quote($filterkey, '/').')/i', '<strong>$1</strong>', $objRefFourn, 1);
 				$label = $objp->label;
-				if ($filterkey && $filterkey != '') $label = preg_replace('/('.preg_quote($filterkey).')/i', '<strong>$1</strong>', $label, 1);
+				if ($filterkey && $filterkey != '') $label = preg_replace('/('.preg_quote($filterkey, '/').')/i', '<strong>$1</strong>', $label, 1);
 
 				$optlabel = $objp->ref;
 				if (!empty($objp->idprodfournprice) && ($objp->ref != $objp->ref_fourn)) {