diff --git a/htdocs/supplier_proposal/class/supplier_proposal.class.php b/htdocs/supplier_proposal/class/supplier_proposal.class.php
index fee21d4365b..503f99b65aa 100644
--- a/htdocs/supplier_proposal/class/supplier_proposal.class.php
+++ b/htdocs/supplier_proposal/class/supplier_proposal.class.php
@@ -2429,7 +2429,7 @@ class SupplierProposal extends CommonObject
 				$dir = dol_buildpath($reldir."core/modules/supplier_proposal/");
 
 				// Load file with numbering class (if found)
-				$mybool |= @include_once $dir.$file;
+				$mybool = ((bool) @include_once $dir.$file) || $mybool;
 			}
 
 			if (!$mybool) {