diff --git a/src/libstore/filetransfer.cc b/src/libstore/filetransfer.cc
index c9f5d6260..aa8f4be1d 100644
--- a/src/libstore/filetransfer.cc
+++ b/src/libstore/filetransfer.cc
@@ -708,7 +708,7 @@ struct curlFileTransfer : public FileTransfer
            download thread and the calling thread. */
 
         struct State {
-            bool quit = false;
+            bool done = false, failed = false;
             std::exception_ptr exc;
             std::string data;
             std::condition_variable avail, request;
@@ -717,18 +717,17 @@ struct curlFileTransfer : public FileTransfer
 
         auto _state = std::make_shared<Sync<State>>();
 
-        /* In case of an exception, wake up the download thread. FIXME:
-           abort the download request. */
+        /* In case of an exception, wake up the download thread. */
         Finally finally([&]() {
             auto state(_state->lock());
-            state->quit = true;
+            state->failed |= std::uncaught_exceptions() != 0;
             state->request.notify_one();
         });
 
         enqueueFileTransfer(request,
             {[_state](std::future<FileTransferResult> fut) {
                 auto state(_state->lock());
-                state->quit = true;
+                state->done = true;
                 try {
                     fut.get();
                 } catch (...) {
@@ -740,7 +739,10 @@ struct curlFileTransfer : public FileTransfer
             [_state, &sink](TransferItem & transfer, std::string_view data) {
                 auto state(_state->lock());
 
-                if (state->quit) return;
+                if (state->failed) {
+                    // actual exception doesn't matter, the other end is already dead
+                    throw std::exception{};
+                }
 
                 if (!state->decompressor) {
                     state->decompressor = makeDecompressionSink(transfer.encoding, sink);
@@ -775,7 +777,7 @@ struct curlFileTransfer : public FileTransfer
 
                 if (state->data.empty()) {
 
-                    if (state->quit) {
+                    if (state->done) {
                         if (state->exc) std::rethrow_exception(state->exc);
                         if (state->decompressor) {
                             state->decompressor->finish();
diff --git a/tests/unit/libstore/filetransfer.cc b/tests/unit/libstore/filetransfer.cc
new file mode 100644
index 000000000..192bf81ef
--- /dev/null
+++ b/tests/unit/libstore/filetransfer.cc
@@ -0,0 +1,32 @@
+#include "filetransfer.hh"
+
+#include <future>
+#include <gtest/gtest.h>
+
+using namespace std::chrono_literals;
+
+namespace nix {
+
+TEST(FileTransfer, exceptionAbortsDownload)
+{
+    struct Done
+    {};
+
+    auto ft = makeFileTransfer();
+
+    LambdaSink broken([](auto block) { throw Done(); });
+
+    ASSERT_THROW(ft->download(FileTransferRequest("file:///dev/zero"), broken), Done);
+
+    // makeFileTransfer returns a ref<>, which cannot be cleared. since we also
+    // can't default-construct it we'll have to overwrite it instead, but we'll
+    // take the raw pointer out first so we can destroy it in a detached thread
+    // (otherwise a failure will stall the process and have it killed by meson)
+    auto reset = std::async(std::launch::async, [&]() { ft = makeFileTransfer(); });
+    EXPECT_EQ(reset.wait_for(10s), std::future_status::ready);
+    // if this did time out we have to leak `reset`.
+    if (reset.wait_for(0s) == std::future_status::timeout) {
+        (void) new auto(std::move(reset));
+    }
+}
+}
diff --git a/tests/unit/meson.build b/tests/unit/meson.build
index 339ac9a4a..f5355cce8 100644
--- a/tests/unit/meson.build
+++ b/tests/unit/meson.build
@@ -113,6 +113,7 @@ libstore_tests_sources = files(
   'libstore/derivation.cc',
   'libstore/derived-path.cc',
   'libstore/downstream-placeholder.cc',
+  'libstore/filetransfer.cc',
   'libstore/machines.cc',
   'libstore/nar-info-disk-cache.cc',
   'libstore/outputs-spec.cc',