diff -Naur -x '*~' --ignore-all-space keepass-2.40/KeePass/App/AppHelp.cs keepass-2.40-enable-local-help/KeePass/App/AppHelp.cs
--- keepass-2.40/KeePass/App/AppHelp.cs	2018-08-12 20:22:06.000000000 +0200
+++ keepass-2.40-enable-local-help/KeePass/App/AppHelp.cs	2018-09-17 19:29:49.875098247 +0200
@@ -67,7 +67,7 @@
 				{
 					string strFile = AppHelp.LocalHelpFile;
 					if(!string.IsNullOrEmpty(strFile))
-						return File.Exists(strFile);
+						return Directory.Exists(@"/usr/share/doc/keepass/Chm/help/");
 				}
 				catch(Exception) { Debug.Assert(false); }
 
@@ -127,18 +127,16 @@
 			string strFile = AppHelp.LocalHelpFile;
 			if(string.IsNullOrEmpty(strFile)) { Debug.Assert(false); return; }
 
-			// Unblock CHM file for proper display of help contents
-			WinUtil.RemoveZoneIdentifier(strFile);
-
-			string strCmd = "\"ms-its:" + strFile;
+			string strCmd = "/usr/share/doc/keepass/Chm/help/";
 			if(!string.IsNullOrEmpty(strTopic))
 			{
-				strCmd += "::/help/" + strTopic + ".html";
+				strCmd += strTopic + ".html";
 
 				if(!string.IsNullOrEmpty(strSection))
 					strCmd += "#" + strSection;
+			} else {
+				strCmd += "../index.html";
 			}
-			strCmd += "\"";
 
 			if(ShowHelpLocalKcv(strCmd)) return;