diff --git a/htdocs/api/index.php b/htdocs/api/index.php
index e10ebba0e62..09f5cdb7cfe 100644
--- a/htdocs/api/index.php
+++ b/htdocs/api/index.php
@@ -252,7 +252,9 @@ if (! empty($reg[1]) && ($reg[1] != 'explorer' || ($reg[2] != '/resources.json'
     }
     else
     {
-        $classfile = str_replace('_', '', preg_replace('/api$/i','', $module));
+    	$tmpmodule = $module;
+    	if ($tmpmodule != 'api') $tmpmodule = preg_replace('/api$/i','', $tmpmodule);
+        $classfile = str_replace('_', '', $tmpmodule);
         if ($module == 'supplierinvoices') $classfile = 'supplier_invoices';
         if ($module == 'supplierorders')   $classfile = 'supplier_orders';
         $dir_part_file = dol_buildpath('/'.$moduledirforclass.'/class/api_'.$classfile.'.class.php', 0, 2);
diff --git a/htdocs/core/lib/functions2.lib.php b/htdocs/core/lib/functions2.lib.php
index 4f1ed15d676..7ba73df91df 100644
--- a/htdocs/core/lib/functions2.lib.php
+++ b/htdocs/core/lib/functions2.lib.php
@@ -2192,7 +2192,8 @@ function cartesianArray(array $input) {
  */
 function getModuleDirForApiClass($module)
 {
-    $moduledirforclass=preg_replace('/api$/i','',$module);
+    $moduledirforclass=$module;
+    if ($moduledirforclass != 'api') $moduledirforclass = preg_replace('/api$/i','',$moduledirforclass);
 
     if ($module == 'contracts') {
     	$moduledirforclass = 'contrat';