diff --git a/core/metamodel.class.php b/core/metamodel.class.php
index a435576f65..b8705ea4cc 100644
--- a/core/metamodel.class.php
+++ b/core/metamodel.class.php
@@ -467,7 +467,7 @@ abstract class MetaModel
 				return self::GetClassIcon($sParentClass, $bImgTag, $sMoreStyles);
 			}
 		}
-		$sIcon = str_replace('/modules/', '/env-'.self::$m_sEnvironment.'/', $sIcon); // Support of pre-2.0 modules
+		$sIcon = str_replace('/modules/', '/env-'.self::$m_sEnvironment.'/', $sIcon ?? ''); // Support of pre-2.0 modules
 		if ($bImgTag && ($sIcon != '')) {
 			$sIcon = "<img src=\"$sIcon\" style=\"vertical-align:middle;$sMoreStyles\"/>";
 		}