--- a/Archiver.st	Wed Dec 18 19:05:58 2019 +0100
+++ b/Archiver.st	Thu Dec 19 14:36:42 2019 +0100
@@ -1,5 +1,3 @@
-"{ Encoding: utf8 }"
-
 "
  COPYRIGHT (c) 2002 by eXept Software AG
               All Rights Reserved
@@ -1610,11 +1608,13 @@
     cmd := self getCommandToListFiles:aColOfFiles.
     cmd isNil ifTrue:[
         "/ no list command configured/found.
-        "/ try smalltalk zipArchive...
-        fn mimeTypeOfContents = 'application/x-zip-compressed' ifTrue:[
-            self useBuiltinArchiver:true.
-            self listFilesUsingBuiltinZipArchiverFrom:fn.
-            ^ self.
+        (Smalltalk at:#ZipArchive) notNil ifTrue:[
+            "/ try smalltalk zipArchive...
+            fn mimeTypeOfContents = 'application/x-zip-compressed' ifTrue:[
+                self useBuiltinArchiver:true.
+                self listFilesUsingBuiltinZipArchiverFrom:fn.
+                ^ self.
+            ]
         ].
     ].
     ^ super listFiles:aColOfFiles.
@@ -1626,7 +1626,7 @@
     |zip members names|
 
     outStream nextPutLine:'dummy headline'.
-    zip := Smalltalk::ZipArchive oldFileNamed:fn.
+    zip := (Smalltalk at:#ZipArchive) oldFileNamed:fn.
     members := zip zipMembersByName.
     names := members keys copyAsOrderedCollection sort.
     names do:[:eachName |