diff --git a/src/commands/diffWith.ts b/src/commands/diffWith.ts
index 90aa063..e536f85 100644
--- a/src/commands/diffWith.ts
+++ b/src/commands/diffWith.ts
@@ -136,7 +136,7 @@ export class DiffWithCommand extends ActiveEditorCommand {
                 args.lhs.title = `${path.basename(args.lhs.uri.fsPath)}${suffix !== '' ? ` (${lhsPrefix}${suffix})` : ''}`;
             }
             if (args.rhs.title === undefined && args.rhs.sha !== GitService.deletedSha) {
-                const suffix = GitService.shortenSha(args.rhs.sha) || '';
+                const suffix = GitService.shortenSha(args.rhs.sha, { uncommitted: 'working tree' }) || '';
                 args.rhs.title = `${path.basename(args.rhs.uri.fsPath)}${suffix !== '' ? ` (${rhsPrefix}${suffix})` : rhsPrefix}`;
             }
 
diff --git a/src/git/git.ts b/src/git/git.ts
index 7052e67..b7d8c0d 100644
--- a/src/git/git.ts
+++ b/src/git/git.ts
@@ -183,7 +183,7 @@ export class Git {
             ref = '';
         }
 
-        const suffix = Strings.truncate(Strings.sanitizeForFileSystem(Git.isSha(ref) ? Git.shortenSha(ref) : ref), 50, '');
+        const suffix = Strings.truncate(Strings.sanitizeForFileSystem(Git.isSha(ref) ? Git.shortenSha(ref)! : ref), 50, '');
         const ext = path.extname(fileName);
 
         const tmp = await import('tmp');
@@ -224,9 +224,11 @@ export class Git {
         return sha === undefined ? false : Git.uncommittedRegex.test(sha);
     }
 
-    static shortenSha(sha: string) {
-        if (Git.isStagedUncommitted(sha)) return 'index';
-        if (Git.isUncommitted(sha)) return '';
+    static shortenSha(sha: string, strings: { deleted?: string, stagedUncommitted?: string, uncommitted?: string } = {}) {
+        strings = { uncommitted: '', stagedUncommitted: 'index', ...strings };
+
+        if (Git.isStagedUncommitted(sha)) return strings.stagedUncommitted;
+        if (Git.isUncommitted(sha)) return strings.uncommitted;
 
         const index = sha.indexOf('^');
         if (index > 6) {
diff --git a/src/git/models/commit.ts b/src/git/models/commit.ts
index 0fd19f3..c96ba02 100644
--- a/src/git/models/commit.ts
+++ b/src/git/models/commit.ts
@@ -122,7 +122,7 @@ export abstract class GitCommit {
     protected _resolvedPreviousFileSha: string | undefined;
 
     get previousFileShortSha(): string {
-        return Git.shortenSha(this.previousFileSha);
+        return Git.shortenSha(this.previousFileSha)!;
     }
 
     get previousSha(): string | undefined {
diff --git a/src/gitService.ts b/src/gitService.ts
index be54ae1..a68ab03 100644
--- a/src/gitService.ts
+++ b/src/gitService.ts
@@ -1452,12 +1452,15 @@ export class GitService extends Disposable {
         return Git.isUncommitted(sha);
     }
 
-    static shortenSha(sha: string | undefined) {
+    static shortenSha(sha: string | undefined, strings: { deleted?: string, stagedUncommitted?: string, uncommitted?: string } = {}) {
         if (sha === undefined) return undefined;
-        if (sha === GitService.deletedSha) return '(deleted)';
+
+        strings = { deleted: '(deleted)', ...strings };
+
+        if (sha === GitService.deletedSha) return strings.deleted;
 
         return Git.isSha(sha) || Git.isStagedUncommitted(sha)
-            ? Git.shortenSha(sha)
+            ? Git.shortenSha(sha, strings)
             : sha;
     }