diff --git a/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests+XCTest.swift b/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests+XCTest.swift
index 8fa219838..221a63211 100644
--- a/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests+XCTest.swift
+++ b/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests+XCTest.swift
@@ -30,6 +30,7 @@ extension HTTP2ClientRequestHandlerTests {
             ("testIdleReadTimeout", testIdleReadTimeout),
             ("testIdleReadTimeoutIsCanceledIfRequestIsCanceled", testIdleReadTimeoutIsCanceledIfRequestIsCanceled),
             ("testWriteHTTPHeadFails", testWriteHTTPHeadFails),
+            ("testChannelBecomesNonWritableDuringHeaderWrite", testChannelBecomesNonWritableDuringHeaderWrite),
         ]
     }
 }
diff --git a/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests.swift b/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests.swift
index e67529ad8..5dfce3f9d 100644
--- a/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests.swift
+++ b/Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests.swift
@@ -345,4 +345,33 @@ class HTTP2ClientRequestHandlerTests: XCTestCase {
             XCTAssertEqual(embedded.isActive, false)
         }
     }
+
+    func testChannelBecomesNonWritableDuringHeaderWrite() throws {
+        try XCTSkipIf(true, "this currently fails and will be fixed in follow up PR")
+        final class ChangeWritabilityOnFlush: ChannelOutboundHandler {
+            typealias OutboundIn = Any
+            func flush(context: ChannelHandlerContext) {
+                context.flush()
+                (context.channel as! EmbeddedChannel).isWritable = false
+                context.fireChannelWritabilityChanged()
+            }
+        }
+        let eventLoopGroup = EmbeddedEventLoopGroup(loops: 1)
+        let eventLoop = eventLoopGroup.next() as! EmbeddedEventLoop
+        let handler = HTTP2ClientRequestHandler(
+            eventLoop: eventLoop
+        )
+        let channel = EmbeddedChannel(handlers: [
+            ChangeWritabilityOnFlush(),
+            handler,
+        ], loop: eventLoop)
+        try channel.connect(to: .init(ipAddress: "127.0.0.1", port: 80)).wait()
+
+        let request = MockHTTPExecutableRequest()
+        // non empty body is important to trigger this bug as we otherwise finish the request in a single flush
+        request.requestFramingMetadata.body = .fixedSize(1)
+        request.raiseErrorIfUnimplementedMethodIsCalled = false
+        channel.writeAndFlush(request, promise: nil)
+        XCTAssertEqual(request.events.map(\.kind), [.willExecuteRequest, .requestHeadSent])
+    }
 }
diff --git a/Tests/AsyncHTTPClientTests/HTTPClientTestUtils.swift b/Tests/AsyncHTTPClientTests/HTTPClientTestUtils.swift
index e50dab3b6..ca24cba1c 100644
--- a/Tests/AsyncHTTPClientTests/HTTPClientTestUtils.swift
+++ b/Tests/AsyncHTTPClientTests/HTTPClientTestUtils.swift
@@ -329,17 +329,32 @@ internal final class HTTPBin<RequestHandler: ChannelInboundHandler> where
         // supports http1.1 connections only, which can be either plain text or encrypted
         case http1_1(ssl: Bool = false, compress: Bool = false)
         // supports http1.1 and http2 connections which must be always encrypted
-        case http2(compress: Bool)
+        case http2(
+            compress: Bool = false,
+            settings: HTTP2Settings? = nil
+        )
 
         // supports request decompression and http response compression
         var compress: Bool {
             switch self {
             case .refuse:
                 return false
-            case .http1_1(ssl: _, compress: let compress), .http2(compress: let compress):
+            case .http1_1(ssl: _, compress: let compress), .http2(compress: let compress, _):
                 return compress
             }
         }
+
+        var httpSettings: HTTP2Settings {
+            switch self {
+            case .http1_1, .http2(_, nil), .refuse:
+                return [
+                    HTTP2Setting(parameter: .maxConcurrentStreams, value: 10),
+                    HTTP2Setting(parameter: .maxHeaderListSize, value: HPACKDecoder.defaultMaxHeaderListSize),
+                ]
+            case .http2(_, .some(let customSettings)):
+                return customSettings
+            }
+        }
     }
 
     enum Proxy {
@@ -565,11 +580,7 @@ internal final class HTTPBin<RequestHandler: ChannelInboundHandler> where
                     // Successful upgrade to HTTP/2. Let the user configure the pipeline.
                     let http2Handler = NIOHTTP2Handler(
                         mode: .server,
-                        initialSettings: [
-                            // TODO: make max concurrent streams configurable
-                            HTTP2Setting(parameter: .maxConcurrentStreams, value: 10),
-                            HTTP2Setting(parameter: .maxHeaderListSize, value: HPACKDecoder.defaultMaxHeaderListSize),
-                        ]
+                        initialSettings: self.mode.httpSettings
                     )
                     let multiplexer = HTTP2StreamMultiplexer(
                         mode: .server,
diff --git a/Tests/AsyncHTTPClientTests/HTTPClientTests+XCTest.swift b/Tests/AsyncHTTPClientTests/HTTPClientTests+XCTest.swift
index f9ddb1c8b..6e84f9d29 100644
--- a/Tests/AsyncHTTPClientTests/HTTPClientTests+XCTest.swift
+++ b/Tests/AsyncHTTPClientTests/HTTPClientTests+XCTest.swift
@@ -144,6 +144,7 @@ extension HTTPClientTests {
             ("testMassiveDownload", testMassiveDownload),
             ("testShutdownWithFutures", testShutdownWithFutures),
             ("testMassiveHeaderHTTP1", testMassiveHeaderHTTP1),
+            ("testMassiveHeaderHTTP2", testMassiveHeaderHTTP2),
         ]
     }
 }
diff --git a/Tests/AsyncHTTPClientTests/HTTPClientTests.swift b/Tests/AsyncHTTPClientTests/HTTPClientTests.swift
index 8e5d5fbfa..54d854bf0 100644
--- a/Tests/AsyncHTTPClientTests/HTTPClientTests.swift
+++ b/Tests/AsyncHTTPClientTests/HTTPClientTests.swift
@@ -3378,4 +3378,33 @@ final class HTTPClientTests: XCTestCaseHTTPClientTestsBaseClass {
 
         XCTAssertNoThrow(try defaultClient.execute(request: request).wait())
     }
+
+    func testMassiveHeaderHTTP2() throws {
+        try XCTSkipIf(true, "this currently crashes and will be fixed in follow up PR")
+        let bin = HTTPBin(.http2(settings: [
+            .init(parameter: .maxConcurrentStreams, value: 100),
+            .init(parameter: .maxHeaderListSize, value: 1024 * 256),
+            .init(parameter: .maxFrameSize, value: 1024 * 256),
+        ]))
+        defer { XCTAssertNoThrow(try bin.shutdown()) }
+
+        let client = HTTPClient(
+            eventLoopGroupProvider: .shared(clientGroup),
+            configuration: .init(certificateVerification: .none)
+        )
+
+        defer { XCTAssertNoThrow(try client.syncShutdown()) }
+
+        var request = try HTTPClient.Request(url: bin.baseURL, method: .POST)
+        // add ~200 KB header
+        let headerValue = String(repeating: "0", count: 1024)
+        for headerID in 0..<200 {
+            request.headers.replaceOrAdd(name: "larg-header-\(headerID)", value: headerValue)
+        }
+
+        // non empty body is important to trigger this bug as we otherwise finish the request in a single flush
+        request.body = .byteBuffer(ByteBuffer(bytes: [0]))
+
+        XCTAssertNoThrow(try client.execute(request: request).wait())
+    }
 }