diff --git a/Applications/Browser/DownloadWidget.cpp b/Applications/Browser/DownloadWidget.cpp
index 71b618656d..a187c68d52 100644
--- a/Applications/Browser/DownloadWidget.cpp
+++ b/Applications/Browser/DownloadWidget.cpp
@@ -59,7 +59,7 @@ DownloadWidget::DownloadWidget(const URL& url)
     m_download->on_progress = [this](Optional<u32> total_size, u32 downloaded_size) {
         did_progress(total_size.value(), downloaded_size);
     };
-    m_download->on_finish = [this](bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String>& response_headers) {
+    m_download->on_finish = [this](bool success, auto& payload, auto payload_storage, auto& response_headers) {
         did_finish(success, payload, payload_storage, response_headers);
     };
 
@@ -156,7 +156,7 @@ void DownloadWidget::did_progress(Optional<u32> total_size, u32 downloaded_size)
     }
 }
 
-void DownloadWidget::did_finish(bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String>& response_headers)
+void DownloadWidget::did_finish(bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers)
 {
     (void)payload;
     (void)payload_storage;
diff --git a/Applications/Browser/DownloadWidget.h b/Applications/Browser/DownloadWidget.h
index 9c632bbfc6..95fec634d5 100644
--- a/Applications/Browser/DownloadWidget.h
+++ b/Applications/Browser/DownloadWidget.h
@@ -44,7 +44,7 @@ private:
     explicit DownloadWidget(const URL&);
 
     void did_progress(Optional<u32> total_size, u32 downloaded_size);
-    void did_finish(bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String>& response_headers);
+    void did_finish(bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers);
 
     URL m_url;
     String m_destination_path;
diff --git a/Libraries/LibProtocol/Download.cpp b/Libraries/LibProtocol/Download.cpp
index 103964a93f..616321df92 100644
--- a/Libraries/LibProtocol/Download.cpp
+++ b/Libraries/LibProtocol/Download.cpp
@@ -53,7 +53,13 @@ void Download::did_finish(Badge<Client>, bool success, u32 total_size, i32 shbuf
         payload = ByteBuffer::wrap(shared_buffer->data(), total_size);
     }
 
-    on_finish(success, payload, move(shared_buffer), response_headers.entries());
+    // FIXME: It's a bit silly that we copy the response headers here just so we can move them into a HashMap with different traits.
+    HashMap<String, String, CaseInsensitiveStringTraits> caseless_response_headers;
+    response_headers.for_each_entry([&](auto& name, auto& value) {
+        caseless_response_headers.set(name, value);
+    });
+
+    on_finish(success, payload, move(shared_buffer), caseless_response_headers);
 }
 
 void Download::did_progress(Badge<Client>, Optional<u32> total_size, u32 downloaded_size)
@@ -61,5 +67,4 @@ void Download::did_progress(Badge<Client>, Optional<u32> total_size, u32 downloa
     if (on_progress)
         on_progress(total_size, downloaded_size);
 }
-
 }
diff --git a/Libraries/LibProtocol/Download.h b/Libraries/LibProtocol/Download.h
index 883406e8b3..4934e54fb9 100644
--- a/Libraries/LibProtocol/Download.h
+++ b/Libraries/LibProtocol/Download.h
@@ -30,6 +30,7 @@
 #include <AK/ByteBuffer.h>
 #include <AK/Function.h>
 #include <AK/RefCounted.h>
+#include <AK/String.h>
 #include <AK/WeakPtr.h>
 #include <LibIPC/Forward.h>
 
@@ -47,7 +48,7 @@ public:
     int id() const { return m_download_id; }
     bool stop();
 
-    Function<void(bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String>& response_headers)> on_finish;
+    Function<void(bool success, const ByteBuffer& payload, RefPtr<SharedBuffer> payload_storage, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers)> on_finish;
     Function<void(Optional<u32> total_size, u32 downloaded_size)> on_progress;
 
     void did_finish(Badge<Client>, bool success, u32 total_size, i32 shbuf_id, const IPC::Dictionary& response_headers);
diff --git a/Libraries/LibWeb/ResourceLoader.cpp b/Libraries/LibWeb/ResourceLoader.cpp
index f8d6be8b51..bbaa45fa62 100644
--- a/Libraries/LibWeb/ResourceLoader.cpp
+++ b/Libraries/LibWeb/ResourceLoader.cpp
@@ -47,7 +47,7 @@ ResourceLoader::ResourceLoader()
 {
 }
 
-void ResourceLoader::load_sync(const URL& url, Function<void(const ByteBuffer&, const HashMap<String, String>& response_headers)> success_callback, Function<void(const String&)> error_callback)
+void ResourceLoader::load_sync(const URL& url, Function<void(const ByteBuffer&, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers)> success_callback, Function<void(const String&)> error_callback)
 {
     Core::EventLoop loop;
 
@@ -66,7 +66,7 @@ void ResourceLoader::load_sync(const URL& url, Function<void(const ByteBuffer&,
     loop.exec();
 }
 
-void ResourceLoader::load(const URL& url, Function<void(const ByteBuffer&, const HashMap<String, String>& response_headers)> success_callback, Function<void(const String&)> error_callback)
+void ResourceLoader::load(const URL& url, Function<void(const ByteBuffer&, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers)> success_callback, Function<void(const String&)> error_callback)
 {
     if (is_port_blocked(url.port())) {
         dbg() << "ResourceLoader::load: Error: blocked port " << url.port() << " for URL: " << url;
diff --git a/Libraries/LibWeb/ResourceLoader.h b/Libraries/LibWeb/ResourceLoader.h
index 74f9e2426e..7bca500a60 100644
--- a/Libraries/LibWeb/ResourceLoader.h
+++ b/Libraries/LibWeb/ResourceLoader.h
@@ -41,8 +41,8 @@ class ResourceLoader : public Core::Object {
 public:
     static ResourceLoader& the();
 
-    void load(const URL&, Function<void(const ByteBuffer&, const HashMap<String, String>& response_headers)> success_callback, Function<void(const String&)> error_callback = nullptr);
-    void load_sync(const URL&, Function<void(const ByteBuffer&, const HashMap<String, String>& response_headers)> success_callback, Function<void(const String&)> error_callback = nullptr);
+    void load(const URL&, Function<void(const ByteBuffer&, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers)> success_callback, Function<void(const String&)> error_callback = nullptr);
+    void load_sync(const URL&, Function<void(const ByteBuffer&, const HashMap<String, String, CaseInsensitiveStringTraits>& response_headers)> success_callback, Function<void(const String&)> error_callback = nullptr);
 
     Function<void()> on_load_counter_change;