diff --git a/src/libstore/build/substitution-goal.cc b/src/libstore/build/substitution-goal.cc
index d8d9ba283..cc4cb3c8c 100644
--- a/src/libstore/build/substitution-goal.cc
+++ b/src/libstore/build/substitution-goal.cc
@@ -217,6 +217,7 @@ void PathSubstitutionGoal::tryToRun()
     promise = std::promise<void>();
 
     thr = std::thread([this]() {
+        auto & fetchPath = subPath ? *subPath : storePath;
         try {
             ReceiveInterrupts receiveInterrupts;
 
@@ -226,10 +227,17 @@ void PathSubstitutionGoal::tryToRun()
             Activity act(*logger, actSubstitute, Logger::Fields{worker.store.printStorePath(storePath), sub->getUri()});
             PushActivity pact(act.id);
 
-            copyStorePath(*sub, worker.store,
-                subPath ? *subPath : storePath, repair, sub->isTrusted ? NoCheckSigs : CheckSigs);
+            copyStorePath(
+                *sub, worker.store, fetchPath, repair, sub->isTrusted ? NoCheckSigs : CheckSigs
+            );
 
             promise.set_value();
+        } catch (const EndOfFile &) {
+            promise.set_exception(std::make_exception_ptr(EndOfFile(
+                "NAR for '%s' fetched from '%s' is incomplete",
+                sub->printStorePath(fetchPath),
+                sub->getUri()
+            )));
         } catch (...) {
             promise.set_exception(std::current_exception());
         }
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index 244ecf256..7c0902978 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -1072,8 +1072,6 @@ void copyStorePath(
         });
         TeeSink tee { sink, progressSink };
         srcStore.narFromPath(storePath, tee);
-    }, [&]() {
-           throw EndOfFile("NAR for '%s' fetched from '%s' is incomplete", srcStore.printStorePath(storePath), srcStore.getUri());
     });
 
     dstStore.addToStore(*info, *source, repair, checkSigs);
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 3a8a01f16..80b111f08 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -266,20 +266,17 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
 }
 
 
-std::unique_ptr<Source> sinkToSource(
-    std::function<void(Sink &)> fun,
-    std::function<void()> eof)
+std::unique_ptr<Source> sinkToSource(std::function<void(Sink &)> fun)
 {
     struct SinkToSource : Source
     {
         typedef boost::coroutines2::coroutine<std::string> coro_t;
 
         std::function<void(Sink &)> fun;
-        std::function<void()> eof;
         std::optional<coro_t::pull_type> coro;
 
-        SinkToSource(std::function<void(Sink &)> fun, std::function<void()> eof)
-            : fun(fun), eof(eof)
+        SinkToSource(std::function<void(Sink &)> fun)
+            : fun(fun)
         {
         }
 
@@ -298,7 +295,9 @@ std::unique_ptr<Source> sinkToSource(
                 });
             }
 
-            if (!*coro) { eof(); abort(); }
+            if (!*coro) {
+                throw EndOfFile("coroutine has finished");
+            }
 
             if (pos == cur.size()) {
                 if (!cur.empty()) {
@@ -317,7 +316,7 @@ std::unique_ptr<Source> sinkToSource(
         }
     };
 
-    return std::make_unique<SinkToSource>(fun, eof);
+    return std::make_unique<SinkToSource>(fun);
 }
 
 
diff --git a/src/libutil/serialise.hh b/src/libutil/serialise.hh
index c9294ba2d..0632e3109 100644
--- a/src/libutil/serialise.hh
+++ b/src/libutil/serialise.hh
@@ -338,11 +338,7 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun);
  * Convert a function that feeds data into a Sink into a Source. The
  * Source executes the function as a coroutine.
  */
-std::unique_ptr<Source> sinkToSource(
-    std::function<void(Sink &)> fun,
-    std::function<void()> eof = []() {
-        throw EndOfFile("coroutine has finished");
-    });
+std::unique_ptr<Source> sinkToSource(std::function<void(Sink &)> fun);
 
 
 void writePadding(size_t len, Sink & sink);
diff --git a/tests/functional/meson.build b/tests/functional/meson.build
index a13dee001..eede1834c 100644
--- a/tests/functional/meson.build
+++ b/tests/functional/meson.build
@@ -182,6 +182,7 @@ functional_tests_scripts = [
   'debugger.sh',
   'test-libstoreconsumer.sh',
   'extra-sandbox-profile.sh',
+  'substitute-truncated-nar.sh',
 ]
 
 # Plugin tests require shared libraries support.
diff --git a/tests/functional/substitute-truncated-nar.sh b/tests/functional/substitute-truncated-nar.sh
new file mode 100644
index 000000000..1ac7efaf6
--- /dev/null
+++ b/tests/functional/substitute-truncated-nar.sh
@@ -0,0 +1,29 @@
+source common.sh
+
+BINARY_CACHE=file://$cacheDir
+
+build() {
+    nix-build --no-out-link "$@" --expr 'derivation {
+        name = "text";
+        system = builtins.currentSystem;
+        builder = "/bin/sh";
+        args = [ "-c" "echo some text to make the nar less empty > $out" ];
+    }'
+}
+
+path=$(build)
+nix copy --to "$BINARY_CACHE" "$path"
+nix-collect-garbage >/dev/null 2>&1
+
+nar=0bylmx35yjy2b1b4k7gjsl7i4vc03cpmryb41grfb1mp40n3hifl.nar.xz
+
+[ -e $cacheDir/nar/$nar ] || fail "long nar missing?"
+
+xzcat $cacheDir/nar/$nar > $TEST_HOME/tmp
+truncate -s $(( $(stat -c %s $TEST_HOME/tmp) - 10 )) $TEST_HOME/tmp
+xz < $TEST_HOME/tmp > $cacheDir/nar/$nar
+
+# Copying back '$path' from the binary cache. This should fail as it is truncated
+if build --option substituters "$BINARY_CACHE" --option require-sigs false -j0; then
+    fail "Importing a truncated nar should fail"
+fi