diff --git a/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/INodeProcess.cs b/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/INodeProcess.cs
index 49baed7bfc..344cab0303 100644
--- a/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/INodeProcess.cs
+++ b/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/INodeProcess.cs
@@ -11,4 +11,4 @@ internal interface INodeProcess : IDisposable
 
         TextReader StandardError { get; }
     }
-}
\ No newline at end of file
+}
diff --git a/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/NodeProcess.cs b/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/NodeProcess.cs
index ee60e92b91..71f4367992 100644
--- a/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/NodeProcess.cs
+++ b/packages/@jsii/dotnet-runtime/src/Amazon.JSII.Runtime/Services/NodeProcess.cs
@@ -4,6 +4,7 @@
 using System.IO;
 using System.Reflection;
 using System.Runtime.Versioning;
+using System.Text;
 using Microsoft.Extensions.Logging;
 
 namespace Amazon.JSII.Runtime.Services
@@ -26,15 +27,19 @@ public NodeProcess(IJsiiRuntimeProvider jsiiRuntimeProvider, ILoggerFactory logg
             if (string.IsNullOrWhiteSpace(runtimePath))
                 runtimePath = jsiiRuntimeProvider.JsiiRuntimePath;
 
+            var utf8 = new UTF8Encoding(false /* no BOM */);
             _process = new Process
             {
                 StartInfo = new ProcessStartInfo
                 {
                     FileName = "node",
-                    Arguments = "--max-old-space-size=4096 " + runtimePath,
+                    Arguments = $"--max-old-space-size=4096 {runtimePath}",
                     RedirectStandardInput = true,
+                    StandardInputEncoding = utf8,
                     RedirectStandardOutput = true,
-                    RedirectStandardError = true
+                    StandardOutputEncoding = utf8,
+                    RedirectStandardError = true,
+                    StandardErrorEncoding = utf8
                 }
             };
 
diff --git a/packages/@jsii/runtime/lib/sync-stdio.ts b/packages/@jsii/runtime/lib/sync-stdio.ts
index 422eb5958e..0bfd15c5a7 100644
--- a/packages/@jsii/runtime/lib/sync-stdio.ts
+++ b/packages/@jsii/runtime/lib/sync-stdio.ts
@@ -5,9 +5,10 @@ const STDOUT_FD = 1;
 const STDERR_FD = 2;
 const INPUT_BUFFER_SIZE = 1024 * 1024; // not related to max line length
 
+const EMPTY_BUFFER = Buffer.alloc(0);
+
 export class SyncStdio {
-  private readonly inputQueue = new Array<string>();
-  private currentLine = '';
+  private bufferedData = EMPTY_BUFFER;
 
   public writeErrorLine(line: string) {
     this.writeBuffer(Buffer.from(`${line}\n`), STDERR_FD);
@@ -19,7 +20,7 @@ export class SyncStdio {
 
   public readLine(): string | undefined {
     const buff = Buffer.alloc(INPUT_BUFFER_SIZE);
-    while (this.inputQueue.length === 0) {
+    while (!this.bufferedData.includes('\n', 0, 'utf-8')) {
       try {
         const read = fs.readSync(STDIN_FD, buff, 0, buff.length, null);
 
@@ -27,16 +28,8 @@ export class SyncStdio {
           return undefined;
         }
 
-        const str = buff.slice(0, read).toString();
-
-        for (const ch of str) {
-          if (ch === '\n') {
-            this.inputQueue.push(this.currentLine);
-            this.currentLine = '';
-          } else {
-            this.currentLine += ch;
-          }
-        }
+        const newData = buff.slice(0, read);
+        this.bufferedData = Buffer.concat([this.bufferedData, newData]);
       } catch (e) {
         // HACK: node may set O_NONBLOCK on it's STDIN depending on what kind of input it is made
         // of (see https://github.com/nodejs/help/issues/2663). When STDIN has O_NONBLOCK, calls may
@@ -52,7 +45,10 @@ export class SyncStdio {
       }
     }
 
-    const next = this.inputQueue.shift();
+    const newLinePos = this.bufferedData.indexOf('\n', 0, 'utf-8');
+    const next = this.bufferedData.slice(0, newLinePos).toString('utf-8');
+    this.bufferedData = this.bufferedData.slice(newLinePos + 1);
+
     return next;
   }