diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index 819a5438eda..c4650465fd9 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -3712,7 +3712,7 @@ class Product extends CommonObject
     			}
             }
 
-			if ($size==1 || $size='small')
+			if ($size==1 || $size=='small')
 			{
 				if ($nbbyrow > 0)
 				{