diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 956a4453d..819cee345 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1245,7 +1245,6 @@ StorePath LocalStore::addToStoreFromDump(
         });
         try {
             got = source.read(dumpBuffer.get() + oldSize, want);
-            if (!got) break;
         } catch (EndOfFile &) {
             inMemory = true;
             break;
diff --git a/src/libutil/serialise.cc b/src/libutil/serialise.cc
index 0f2febaed..d203a01bf 100644
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -246,9 +246,8 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
                     LambdaSource source([&](char * out, size_t out_len) {
                         if (cur.empty()) {
                             yield();
-                            if (yield.get()) {
-                                return (size_t) 0;
-                            }
+                            if (yield.get())
+                                throw EndOfFile("coroutine has finished");
                         }
 
                         size_t n = std::min(cur.size(), out_len);
@@ -271,12 +270,12 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
         void finish() override
         {
             if (!coro) return;
-            //if (!*coro) abort();
+            if (!*coro) abort();
             {
                 CoroutineContext ctx;
                 (*coro)(true);
             }
-            //if (*coro) abort();
+            if (*coro) abort();
         }
     };