diff --git a/htdocs/comm/propal/class/propal.class.php b/htdocs/comm/propal/class/propal.class.php
index 97f818d82a3..04b4a6e99b2 100644
--- a/htdocs/comm/propal/class/propal.class.php
+++ b/htdocs/comm/propal/class/propal.class.php
@@ -3615,7 +3615,7 @@ class Propal extends CommonObject
 				$dir = dol_buildpath($reldir."core/modules/propale/");
 
 				// Load file with numbering class (if found)
-				$mybool |= @include_once $dir.$file;
+				$mybool = ((bool) @include_once $dir.$file) || $mybool;
 			}
 
 			if (!$mybool) {