diff --git a/htdocs/core/class/html.formfile.class.php b/htdocs/core/class/html.formfile.class.php
index f4163a889f0..5a55b3a8a9c 100644
--- a/htdocs/core/class/html.formfile.class.php
+++ b/htdocs/core/class/html.formfile.class.php
@@ -860,10 +860,8 @@ class FormFile
 						print '<td align="center">';
 						if (image_format_supported($file['name']) > 0)
 						{
-						    $minifile=getImageFileNameForSize($file['name'], '_mini', '.png'); // Thumbs are created with filename in lower case and with .png extension
-						    //print $relativepath.'<br>';
-						    //print $file['path'].'/'.$minifile.'<br>';
-						    if (! dol_is_file($file['path'].'/'.$minifile)) $minifile=getImageFileNameForSize($file['name'], '_mini', '.'.$fileinfo['extension']); // For old thumbs
+						    $minifile=getImageFileNameForSize($file['name'], '_mini'); // For new thumbs using same ext (in lower case howerver) than original
+						    if (! dol_is_file($file['path'].'/'.$minifile)) $minifile=getImageFileNameForSize($file['name'], '_mini', '.png'); // For backward compatibility of old thumbs that were created with filename in lower case and with .png extension
 						    //print $file['path'].'/'.$minifile.'<br>';
 						    print '<a href="'.DOL_URL_ROOT.'/viewimage.php?modulepart='.$modulepart.'&file='.urlencode($relativepath.$fileinfo['filename'].'.'.strtolower($fileinfo['extension'])).'" class="aphoto" target="_blank">';
 							print '<img border="0" height="'.$maxheightmini.'" src="'.DOL_URL_ROOT.'/viewimage.php?modulepart='.$modulepart.'&file='.urlencode($relativepath.$minifile).'" title="">';
diff --git a/htdocs/product/class/product.class.php b/htdocs/product/class/product.class.php
index 982b109da99..7b3f1750003 100644
--- a/htdocs/product/class/product.class.php
+++ b/htdocs/product/class/product.class.php
@@ -3676,7 +3676,7 @@ class Product extends CommonObject
     					if ($size == 1 || $size == 'small') {   // Format vignette
 
     						// Find name of thumb file
-    						$photo_vignette=basename(getImageFileNameForSize($dir.$file, '_small', '.png'));
+    						$photo_vignette=basename(getImageFileNameForSize($dir.$file, '_small'));
     						if (! dol_is_file($dirthumb.$photo_vignette)) $photo_vignette='';
     						
     						// Get filesize of original file