diff --git a/src/lsp.cc b/src/lsp.cc
index 1559ef42..f687c085 100644
--- a/src/lsp.cc
+++ b/src/lsp.cc
@@ -14,16 +14,16 @@ namespace ccls {
 void Reflect(JsonReader &vis, RequestId &v) {
   if (vis.m->IsInt64()) {
     v.type = RequestId::kInt;
-    v.value = int(vis.m->GetInt64());
+    v.value = std::to_string(int(vis.m->GetInt64()));
   } else if (vis.m->IsInt()) {
     v.type = RequestId::kInt;
-    v.value = vis.m->GetInt();
+    v.value = std::to_string(vis.m->GetInt());
   } else if (vis.m->IsString()) {
     v.type = RequestId::kString;
-    v.value = atoll(vis.m->GetString());
+    v.value = vis.m->GetString();
   } else {
     v.type = RequestId::kNone;
-    v.value = -1;
+    v.value.clear();
   }
 }
 
@@ -33,11 +33,10 @@ void Reflect(JsonWriter &visitor, RequestId &value) {
     visitor.Null();
     break;
   case RequestId::kInt:
-    visitor.Int(value.value);
+    visitor.Int(atoll(value.value.c_str()));
     break;
   case RequestId::kString:
-    auto s = std::to_string(value.value);
-    visitor.String(s.c_str(), s.size());
+    visitor.String(value.value.c_str(), value.value.size());
     break;
   }
 }
diff --git a/src/lsp.hh b/src/lsp.hh
index bf78f6c7..4b4c4c34 100644
--- a/src/lsp.hh
+++ b/src/lsp.hh
@@ -11,6 +11,7 @@
 
 #include <chrono>
 #include <iosfwd>
+#include <string>
 
 namespace ccls {
 struct RequestId {
@@ -19,7 +20,7 @@ struct RequestId {
   enum Type { kNone, kInt, kString };
   Type type = kNone;
 
-  int value = -1;
+  std::string value;
 
   bool Valid() const { return type != kNone; }
 };
diff --git a/src/pipeline.cc b/src/pipeline.cc
index 298f55d2..14f9341e 100644
--- a/src/pipeline.cc
+++ b/src/pipeline.cc
@@ -799,11 +799,10 @@ static void Reply(RequestId id, const char *key,
     w.Null();
     break;
   case RequestId::kInt:
-    w.Int(id.value);
+    w.Int(atoll(id.value.c_str()));
     break;
   case RequestId::kString:
-    auto s = std::to_string(id.value);
-    w.String(s.c_str(), s.length());
+    w.String(id.value.c_str(), id.value.size());
     break;
   }
   w.Key(key);