diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index e256ad1de..c89b5f5b3 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -264,14 +264,8 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     TrustedFlag trusted, RecursiveFlag recursive, WorkerProto::Version clientVersion,
     Source & from, BufferedSink & to, WorkerProto::Op op)
 {
-    WorkerProto::ReadConn rconn {
-        .from = from,
-        .version = clientVersion,
-    };
-    WorkerProto::WriteConn wconn {
-        .to = to,
-        .version = clientVersion,
-    };
+    WorkerProto::ReadConn rconn{from, clientVersion};
+    WorkerProto::WriteConn wconn{to, clientVersion};
 
     switch (op) {
 
@@ -1030,10 +1024,7 @@ void processConnection(
         auto temp = trusted
             ? store->isTrustedClient()
             : std::optional { NotTrusted };
-        WorkerProto::WriteConn wconn {
-            .to = to,
-            .version = clientVersion,
-        };
+        WorkerProto::WriteConn wconn {to, clientVersion};
         WorkerProto::write(*store, wconn, temp);
     }
 
diff --git a/src/libstore/remote-store-connection.hh b/src/libstore/remote-store-connection.hh
index 082874cec..1647afd0d 100644
--- a/src/libstore/remote-store-connection.hh
+++ b/src/libstore/remote-store-connection.hh
@@ -68,10 +68,7 @@ struct RemoteStore::Connection
      */
     operator WorkerProto::ReadConn ()
     {
-        return WorkerProto::ReadConn {
-            .from = from,
-            .version = daemonVersion,
-        };
+        return WorkerProto::ReadConn {from, daemonVersion};
     }
 
     /**
@@ -84,10 +81,7 @@ struct RemoteStore::Connection
      */
     operator WorkerProto::WriteConn ()
     {
-        return WorkerProto::WriteConn {
-            .to = to,
-            .version = daemonVersion,
-        };
+        return WorkerProto::WriteConn {to, daemonVersion};
     }
 
     virtual ~Connection();
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index 82181b921..d445cbcb6 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -466,7 +466,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
             sink
                 << exportMagic
                 << printStorePath(info.path);
-            WorkerProto::WriteConn nested { .to = sink, .version = conn->daemonVersion };
+            WorkerProto::WriteConn nested { sink, conn->daemonVersion };
             WorkerProto::write(*this, nested, info.references);
             sink
                 << (info.deriver ? printStorePath(*info.deriver) : "")
@@ -511,14 +511,13 @@ void RemoteStore::addMultipleToStore(
     RepairFlag repair,
     CheckSigsFlag checkSigs)
 {
+    auto remoteVersion = getProtocol();
+
     auto source = sinkToSource([&](Sink & sink) {
         sink << pathsToCopy.size();
         for (auto & [pathInfo, pathSource] : pathsToCopy) {
             WorkerProto::Serialise<ValidPathInfo>::write(*this,
-                 WorkerProto::WriteConn {
-                     .to = sink,
-                     .version = 16,
-                 },
+                 WorkerProto::WriteConn {sink, remoteVersion},
                  pathInfo);
             pathSource->drainInto(sink);
         }
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index e0e842060..a10e5df0a 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -368,15 +368,14 @@ void Store::addMultipleToStore(
     RepairFlag repair,
     CheckSigsFlag checkSigs)
 {
+    auto remoteVersion = getProtocol();
+
     auto expected = readNum<uint64_t>(source);
     for (uint64_t i = 0; i < expected; ++i) {
-        // FIXME we should not be using the worker protocol here, let
-        // alone the worker protocol with a hard-coded version!
+        // FIXME we should not be using the worker protocol here at all!
         auto info = WorkerProto::Serialise<ValidPathInfo>::read(*this,
-            WorkerProto::ReadConn {
-                .from = source,
-                .version = 16,
-            });
+            WorkerProto::ReadConn {source, remoteVersion}
+        );
         info.ultimate = false;
         addToStore(info, source, repair, checkSigs);
     }
diff --git a/src/libstore/worker-protocol.hh b/src/libstore/worker-protocol.hh
index cc083a551..5f24c189f 100644
--- a/src/libstore/worker-protocol.hh
+++ b/src/libstore/worker-protocol.hh
@@ -72,6 +72,10 @@ struct WorkerProto
     struct ReadConn {
         Source & from;
         Version version;
+
+        ReadConn(Source & from, Version version) : from(from), version(version) {
+            assert(version >= MIN_SUPPORTED_WORKER_PROTO_VERSION);
+        }
     };
 
     /**
@@ -81,6 +85,10 @@ struct WorkerProto
     struct WriteConn {
         Sink & to;
         Version version;
+
+        WriteConn(Sink & to, Version version) : to(to), version(version) {
+            assert(version >= MIN_SUPPORTED_WORKER_PROTO_VERSION);
+        }
     };
 
     /**
diff --git a/tests/unit/libstore/protocol.hh b/tests/unit/libstore/protocol.hh
index 7fdd3e11c..f480f4ad1 100644
--- a/tests/unit/libstore/protocol.hh
+++ b/tests/unit/libstore/protocol.hh
@@ -39,10 +39,8 @@ public:
                 StringSource from { expected };
                 Proto::template Serialise<T>::read(
                     *LibStoreTest::store,
-                    typename Proto::ReadConn {
-                        .from = from,
-                        .version = version,
-                    });
+                    typename Proto::ReadConn {from, version}
+                );
             });
 
             ASSERT_EQ(got, value);
@@ -60,10 +58,7 @@ public:
         StringSink to;
         Proto::write(
             *LibStoreTest::store,
-            typename Proto::WriteConn {
-                .to = to,
-                .version = version,
-            },
+            typename Proto::WriteConn {to, version},
             value);
 
         if (testAccept())