diff --git a/src/lint/latex-formatter/latexindent.ts b/src/lint/latex-formatter/latexindent.ts
index 1469fda94..da53266ec 100644
--- a/src/lint/latex-formatter/latexindent.ts
+++ b/src/lint/latex-formatter/latexindent.ts
@@ -156,15 +156,19 @@ function format(document: vscode.TextDocument, range?: vscode.Range): Thenable<v
         logger.logCommand('Formatting LaTeX.', formatter, args)
         const worker = cs.spawn(formatter, args, { stdio: 'pipe', cwd: documentDirectory })
         // handle stdout/stderr
-        const stdoutBuffer: string[] = []
-        const stderrBuffer: string[] = []
-        worker.stdout.on('data', (chunk: Buffer | string) => stdoutBuffer.push(chunk.toString()))
-        worker.stderr.on('data', (chunk: Buffer | string) => stderrBuffer.push(chunk.toString()))
+        const stdoutBuffer: Buffer[] = []
+        const stderrBuffer: Buffer[] = []
+        worker.stdout.on('data', (chunk: Buffer | string) => {
+            stdoutBuffer.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk))
+        })
+        worker.stderr.on('data', (chunk: Buffer | string) => {
+            stderrBuffer.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk))
+        })
         worker.on('error', err => {
             removeTemporaryFiles()
             void logger.showErrorMessage('Formatting failed. Please refer to LaTeX Workshop Output for details.')
             logger.log(`Formatting failed: ${err.message}`)
-            logger.log(`stderr: ${stderrBuffer.join('')}`)
+            logger.log(`stderr: ${Buffer.concat(stderrBuffer).toString()}`)
             resolve(undefined)
         })
         worker.on('close', code => {
@@ -172,10 +176,10 @@ function format(document: vscode.TextDocument, range?: vscode.Range): Thenable<v
             if (code !== 0) {
                 void logger.showErrorMessage('Formatting failed. Please refer to LaTeX Workshop Output for details.')
                 logger.log(`Formatting failed with exit code ${code}`)
-                logger.log(`stderr: ${stderrBuffer.join('')}`)
+                logger.log(`stderr: ${Buffer.concat(stderrBuffer).toString()}`)
                 return resolve(undefined)
             }
-            const stdout = stdoutBuffer.join('')
+            const stdout = Buffer.concat(stdoutBuffer).toString()
             if (stdout !== '') {
                 const edit = vscode.TextEdit.replace(range ?? document.validateRange(new vscode.Range(0, 0, Number.MAX_VALUE, Number.MAX_VALUE)), stdout)
                 logger.log('Formatted ' + document.fileName)
diff --git a/src/lint/latex-formatter/tex-fmt.ts b/src/lint/latex-formatter/tex-fmt.ts
index ffa2fd4ca..e146b5d22 100644
--- a/src/lint/latex-formatter/tex-fmt.ts
+++ b/src/lint/latex-formatter/tex-fmt.ts
@@ -15,9 +15,9 @@ async function formatDocument(document: vscode.TextDocument, range?: vscode.Rang
     const args = [...(config.get('formatting.tex-fmt.args') as string[]), '--stdin']
     const process = lw.external.spawn(program, args, { cwd: path.dirname(document.uri.fsPath) })
 
-    let stdout: string = ''
+    let stdout: Buffer = Buffer.alloc(0)
     process.stdout?.on('data', (msg: Buffer | string) => {
-        stdout += msg
+        stdout = Buffer.concat([stdout, Buffer.isBuffer(msg) ? msg : Buffer.from(msg)])
     })
 
     const promise = new Promise<vscode.TextEdit | undefined>(resolve => {
@@ -33,12 +33,13 @@ async function formatDocument(document: vscode.TextDocument, range?: vscode.Rang
                 logger.showErrorMessage(`${program} returned ${code} . Be cautious on the edits.`)
                 resolve(undefined)
             }
+            let stdoutStr = stdout.toString()
             // tex-fmt adds an extra newline at the end
-            if (stdout.endsWith('\n\n')) {
-                stdout = stdout.slice(0, -1)
+            if (stdoutStr.endsWith('\n\n')) {
+                stdoutStr = stdoutStr.slice(0, -1)
             }
             logger.log(`Formatted using ${program} .`)
-            resolve(vscode.TextEdit.replace(range ?? document.validateRange(new vscode.Range(0, 0, Number.MAX_VALUE, Number.MAX_VALUE)), stdout))
+            resolve(vscode.TextEdit.replace(range ?? document.validateRange(new vscode.Range(0, 0, Number.MAX_VALUE, Number.MAX_VALUE)), stdoutStr))
         })
     })