diff --git a/Sources/HummingbirdCompression/CompressedBodyWriter.swift b/Sources/HummingbirdCompression/CompressedBodyWriter.swift
index 3e721f2..7e2cc56 100644
--- a/Sources/HummingbirdCompression/CompressedBodyWriter.swift
+++ b/Sources/HummingbirdCompression/CompressedBodyWriter.swift
@@ -18,7 +18,7 @@ import Logging
 
 // ResponseBodyWriter that writes a compressed version of the response to a parent writer
 final class CompressedBodyWriter<ParentWriter: ResponseBodyWriter & Sendable>: ResponseBodyWriter {
-    let parentWriter: ParentWriter
+    var parentWriter: ParentWriter
     let compressor: NIOCompressor
     var lastBuffer: ByteBuffer?
     let logger: Logger
diff --git a/Tests/HummingbirdCompressionTests/CompressionTests.swift b/Tests/HummingbirdCompressionTests/CompressionTests.swift
index 56ee789..31f9745 100644
--- a/Tests/HummingbirdCompressionTests/CompressionTests.swift
+++ b/Tests/HummingbirdCompressionTests/CompressionTests.swift
@@ -136,10 +136,10 @@ class HummingBirdCompressionTests: XCTestCase {
             let bufferSize: Int
 
             struct Writer: ResponseBodyWriter {
-                let parentWriter: any ResponseBodyWriter
+                var parentWriter: any ResponseBodyWriter
                 let bufferSize: Int
 
-                func write(_ buffer: ByteBuffer) async throws {
+                mutating func write(_ buffer: ByteBuffer) async throws {
                     XCTAssertLessThanOrEqual(buffer.capacity, self.bufferSize)
                     try await self.parentWriter.write(buffer)
                 }