From b85ccd28d8585bdbc6b7c37af9acc91677ba9fd8 Mon Sep 17 00:00:00 2001
From: Adam Hathcock <ADH@chersoft.com>
Date: Mon, 9 Nov 2026 11:20:50 +0000
Subject: [PATCH] Fix netstandard2.0/net48 build in writable archive key
 normalisation

string.StartsWith(char) is not available on netstandard2.0 or net48,
so those targets failed to compile after 990186ac.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 src/SharpCompress/Archives/AbstractWritableArchive.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/SharpCompress/Archives/AbstractWritableArchive.cs b/src/SharpCompress/Archives/AbstractWritableArchive.cs
index 42ff5d5d..f2a7ac87 100644
--- a/src/SharpCompress/Archives/AbstractWritableArchive.cs
+++ b/src/SharpCompress/Archives/AbstractWritableArchive.cs
@@ -170,7 +170,7 @@ public abstract partial class AbstractWritableArchive<TEntry, TVolume, TOptions>
             }
             return key.Trim('/');
         }
-        return key.StartsWith('/') ? key.Substring(1) : key;
+        return key.Length > 0 && key[0] == '/' ? key.Substring(1) : key;
     }
 
     ValueTask IWritableAsyncArchive.RemoveEntryAsync(IArchiveEntry entry) =>