diff --git a/NucleicBroker.Tests/OutboundWriterTests.cs b/NucleicBroker.Tests/OutboundWriterTests.cs
index 68dc7d0..d96e6dd 100644
--- a/NucleicBroker.Tests/OutboundWriterTests.cs
+++ b/NucleicBroker.Tests/OutboundWriterTests.cs
@@ -33,6 +33,24 @@ public sealed class OutboundWriterTests
         Assert.Equal("onetwo", decoded);
     }
 
+    [Fact]
+    public async Task FramesLinesWithBareLineFeed()
+    {
+        // The wire is LF-framed on every host (docs/WINDOWS_PORT.md §3.3). TextWriter.NewLine
+        // would otherwise be CRLF on Windows, hiding a stray \r inside every line hostd parses.
+        // Forcing CRLF on the sink reproduces the Windows default on any platform, so this
+        // pins the framing even when CI runs the suite on Linux.
+        var captured = new StringWriter { NewLine = "\r\n" };
+        var writer = new OutboundWriter(captured);
+        writer.EnqueueJson("""{"a":1}""");
+        writer.EnqueueProcOutput(1, stderr: false, "one"u8);
+        await writer.CompleteAsync();
+
+        var text = captured.ToString();
+        Assert.DoesNotContain('\r', text);
+        Assert.EndsWith("\n", text);
+    }
+
     [Fact]
     public async Task StderrAndStdoutChunksNeverMerge()
     {
diff --git a/NucleicBroker/OutboundWriter.cs b/NucleicBroker/OutboundWriter.cs
index 982a2ed..967b987 100644
--- a/NucleicBroker/OutboundWriter.cs
+++ b/NucleicBroker/OutboundWriter.cs
@@ -26,6 +26,10 @@ public sealed class OutboundWriter
     public OutboundWriter(TextWriter output)
     {
         this.output = output;
+        // NDJSON is LF-framed on the wire (docs/WINDOWS_PORT.md §3.3). TextWriter.NewLine
+        // defaults to Environment.NewLine — CRLF here — which would append a stray \r to
+        // every line hostd's JSONRPCConnection reads. We own this writer, so pin it.
+        this.output.NewLine = "\n";
         loop = Task.Run(DrainAsync);
     }