diff --git a/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.h b/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.h
--- a/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.h
+++ b/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.h
@@ -38,10 +38,15 @@
   Marshaller() = delete;
   Marshaller(llvm::StringRef RemoteIndexRoot, llvm::StringRef LocalIndexRoot);
 
-  clangd::FuzzyFindRequest fromProtobuf(const FuzzyFindRequest *Request);
   llvm::Optional<clangd::Symbol> fromProtobuf(const Symbol &Message);
   llvm::Optional<clangd::Ref> fromProtobuf(const Ref &Message);
 
+  llvm::Optional<clangd::LookupRequest>
+  fromProtobuf(const LookupRequest *Message);
+  llvm::Optional<clangd::FuzzyFindRequest>
+  fromProtobuf(const FuzzyFindRequest *Message);
+  llvm::Optional<clangd::RefsRequest> fromProtobuf(const RefsRequest *Message);
+
   /// toProtobuf() functions serialize native clangd types and strip IndexRoot
   /// from the file paths specific to indexing machine. fromProtobuf() functions
   /// deserialize clangd types and translate relative paths into machine-native
diff --git a/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp b/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp
--- a/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp
+++ b/clang-tools-extra/clangd/index/remote/marshalling/Marshalling.cpp
@@ -17,6 +17,7 @@
 #include "index/SymbolOrigin.h"
 #include "support/Logger.h"
 #include "clang/Index/IndexSymbol.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallString.h"
@@ -30,6 +31,24 @@
 namespace clangd {
 namespace remote {
 
+namespace {
+
+template <typename MessageT>
+llvm::Optional<llvm::DenseSet<SymbolID>> getIDs(MessageT *Message) {
+  llvm::DenseSet<SymbolID> Result;
+  for (const auto &ID : Message->ids()) {
+    auto SID = SymbolID::fromStr(StringRef(ID));
+    if (!SID) {
+      elog("Invalid SymbolID {1}", SID.takeError());
+      return llvm::None;
+    }
+    Result.insert(*SID);
+  }
+  return Result;
+}
+
+} // namespace
+
 Marshaller::Marshaller(llvm::StringRef RemoteIndexRoot,
                        llvm::StringRef LocalIndexRoot)
     : Strings(Arena) {
@@ -49,27 +68,54 @@
   assert(!RemoteIndexRoot.empty() || !LocalIndexRoot.empty());
 }
 
-clangd::FuzzyFindRequest
-Marshaller::fromProtobuf(const FuzzyFindRequest *Request) {
+llvm::Optional<clangd::LookupRequest>
+Marshaller::fromProtobuf(const LookupRequest *Message) {
+  clangd::LookupRequest Req;
+  auto IDs = getIDs(Message);
+  if (!IDs) {
+    elog("Cannot parse LookupRequest from protobuf: invalid Symbol IDs");
+    return llvm::None;
+  }
+  Req.IDs = std::move(*IDs);
+  return Req;
+}
+
+llvm::Optional<clangd::FuzzyFindRequest>
+Marshaller::fromProtobuf(const FuzzyFindRequest *Message) {
   assert(RemoteIndexRoot);
   clangd::FuzzyFindRequest Result;
-  Result.Query = Request->query();
-  for (const auto &Scope : Request->scopes())
+  Result.Query = Message->query();
+  for (const auto &Scope : Message->scopes())
     Result.Scopes.push_back(Scope);
-  Result.AnyScope = Request->any_scope();
-  if (Request->limit())
-    Result.Limit = Request->limit();
-  Result.RestrictForCodeCompletion = Request->restricted_for_code_completion();
-  for (const auto &Path : Request->proximity_paths()) {
+  Result.AnyScope = Message->any_scope();
+  if (Message->limit())
+    Result.Limit = Message->limit();
+  Result.RestrictForCodeCompletion = Message->restricted_for_code_completion();
+  for (const auto &Path : Message->proximity_paths()) {
     llvm::SmallString<256> LocalPath = llvm::StringRef(*RemoteIndexRoot);
     llvm::sys::path::append(LocalPath, Path);
     Result.ProximityPaths.push_back(std::string(LocalPath));
   }
-  for (const auto &Type : Request->preferred_types())
+  for (const auto &Type : Message->preferred_types())
     Result.ProximityPaths.push_back(Type);
   return Result;
 }
 
+llvm::Optional<clangd::RefsRequest>
+Marshaller::fromProtobuf(const RefsRequest *Message) {
+  clangd::RefsRequest Req;
+  auto IDs = getIDs(Message);
+  if (!IDs) {
+    elog("Cannot parse RefsRequest from protobuf: invalid Symbol IDs");
+    return llvm::None;
+  }
+  Req.IDs = std::move(*IDs);
+  Req.Filter = static_cast<RefKind>(Message->filter());
+  if (Message->limit())
+    Req.Limit = Message->limit();
+  return Req;
+}
+
 llvm::Optional<clangd::Symbol> Marshaller::fromProtobuf(const Symbol &Message) {
   if (!Message.has_info() || !Message.has_canonical_declaration()) {
     elog("Cannot convert Symbol from protobuf (missing info, definition or "
@@ -157,8 +203,7 @@
   RPCRequest.set_restricted_for_code_completion(From.RestrictForCodeCompletion);
   for (const auto &Path : From.ProximityPaths) {
     llvm::SmallString<256> RelativePath = llvm::StringRef(Path);
-    if (llvm::sys::path::replace_path_prefix(RelativePath, *LocalIndexRoot,
-                                             ""))
+    if (llvm::sys::path::replace_path_prefix(RelativePath, *LocalIndexRoot, ""))
       RPCRequest.add_proximity_paths(llvm::sys::path::convert_to_slash(
           RelativePath, llvm::sys::path::Style::posix));
   }
diff --git a/clang-tools-extra/clangd/index/remote/server/Server.cpp b/clang-tools-extra/clangd/index/remote/server/Server.cpp
--- a/clang-tools-extra/clangd/index/remote/server/Server.cpp
+++ b/clang-tools-extra/clangd/index/remote/server/Server.cpp
@@ -59,14 +59,10 @@
   grpc::Status Lookup(grpc::ServerContext *Context,
                       const LookupRequest *Request,
                       grpc::ServerWriter<LookupReply> *Reply) override {
-    clangd::LookupRequest Req;
-    for (const auto &ID : Request->ids()) {
-      auto SID = SymbolID::fromStr(StringRef(ID));
-      if (!SID)
-        return grpc::Status::CANCELLED;
-      Req.IDs.insert(*SID);
-    }
-    Index->lookup(Req, [&](const clangd::Symbol &Sym) {
+    const auto Req = ProtobufMarshaller->fromProtobuf(Request);
+    if (!Req)
+      return grpc::Status::CANCELLED;
+    Index->lookup(*Req, [&](const clangd::Symbol &Sym) {
       auto SerializedSymbol = ProtobufMarshaller->toProtobuf(Sym);
       if (!SerializedSymbol)
         return;
@@ -84,7 +80,9 @@
                          const FuzzyFindRequest *Request,
                          grpc::ServerWriter<FuzzyFindReply> *Reply) override {
     const auto Req = ProtobufMarshaller->fromProtobuf(Request);
-    bool HasMore = Index->fuzzyFind(Req, [&](const clangd::Symbol &Sym) {
+    if (!Req)
+      return grpc::Status::CANCELLED;
+    bool HasMore = Index->fuzzyFind(*Req, [&](const clangd::Symbol &Sym) {
       auto SerializedSymbol = ProtobufMarshaller->toProtobuf(Sym);
       if (!SerializedSymbol)
         return;
@@ -100,14 +98,10 @@
 
   grpc::Status Refs(grpc::ServerContext *Context, const RefsRequest *Request,
                     grpc::ServerWriter<RefsReply> *Reply) override {
-    clangd::RefsRequest Req;
-    for (const auto &ID : Request->ids()) {
-      auto SID = SymbolID::fromStr(StringRef(ID));
-      if (!SID)
-        return grpc::Status::CANCELLED;
-      Req.IDs.insert(*SID);
-    }
-    bool HasMore = Index->refs(Req, [&](const clangd::Ref &Reference) {
+    const auto Req = ProtobufMarshaller->fromProtobuf(Request);
+    if (!Req)
+      return grpc::Status::CANCELLED;
+    bool HasMore = Index->refs(*Req, [&](const clangd::Ref &Reference) {
       auto SerializedRef = ProtobufMarshaller->toProtobuf(Reference);
       if (!SerializedRef)
         return;
diff --git a/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp b/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp
--- a/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp
+++ b/clang-tools-extra/clangd/unittests/remote/MarshallingTests.cpp
@@ -289,7 +289,8 @@
   auto Serialized = ProtobufMarshaller.toProtobuf(Request);
   EXPECT_EQ(Serialized.proximity_paths_size(), 2);
   auto Deserialized = ProtobufMarshaller.fromProtobuf(&Serialized);
-  EXPECT_THAT(Deserialized.ProximityPaths,
+  ASSERT_TRUE(Deserialized);
+  EXPECT_THAT(Deserialized->ProximityPaths,
               testing::ElementsAre(testPath("remote/Header.h"),
                                    testPath("remote/subdir/OtherHeader.h")));
 }