diff --git a/src/message_handler.cc b/src/message_handler.cc
index 27999882..722f048a 100644
--- a/src/message_handler.cc
+++ b/src/message_handler.cc
@@ -148,20 +148,18 @@ void EmitSemanticHighlighting(QueryDatabase* db,
         break;
       }
       case SymbolKind::Var: {
-        QueryVar& var = db->GetVar(sym);
-        if (!var.def)
-          continue;  // applies to for loop
-        kind = var.def->kind;
-        storage = var.def->storage;
-        detailed_name = var.def->ShortName();
+        if (const QueryVar::Def* def = db->GetVar(sym).AnyDef()) {
+          kind = def->kind;
+          storage = def->storage;
+          detailed_name = def->ShortName();
+        }
         break;
       }
       case SymbolKind::Type: {
-        QueryType& type = db->GetType(sym);
-        if (!type.def)
-          continue;  // applies to for loop
-        kind = type.def->kind;
-        detailed_name = type.def->detailed_name;
+        if (const QueryType::Def* def = db->GetType(sym).AnyDef()) {
+          kind = def->kind;
+          detailed_name = def->detailed_name;
+        }
         break;
       }
       default:
diff --git a/src/messages/cquery_member_hierarchy.cc b/src/messages/cquery_member_hierarchy.cc
index 0f0322e0..59cb56d6 100644
--- a/src/messages/cquery_member_hierarchy.cc
+++ b/src/messages/cquery_member_hierarchy.cc
@@ -56,17 +56,19 @@ BuildInitial(QueryDatabase* db, WorkingFiles* working_files, QueryTypeId root) {
 std::vector<Out_CqueryMemberHierarchy::Entry>
 ExpandNode(QueryDatabase* db, WorkingFiles* working_files, QueryTypeId root) {
   QueryType& root_type = db->types[root.id];
-  if (!root_type.def)
+  const QueryType::Def* def = root_type.AnyDef();
+  if (!def)
     return {};
 
   std::vector<Out_CqueryMemberHierarchy::Entry> ret;
-  EachWithGen(db->vars, root_type.def->vars, [&](QueryVar& var) {
+  EachWithGen(db->vars, def->vars, [&](QueryVar& var) {
+    const QueryVar::Def* def1 = var.AnyDef();
     Out_CqueryMemberHierarchy::Entry entry;
-    entry.name = var.def->ShortName();
-    entry.type_id = var.def->type ? *var.def->type : QueryTypeId();
-    if (var.def->spell) {
+    entry.name = def1->ShortName();
+    entry.type_id = def1->type ? *def1->type : QueryTypeId();
+    if (def->spell) {
       optional<lsLocation> loc =
-          GetLsLocation(db, working_files, *var.def->spell);
+          GetLsLocation(db, working_files, *def1->spell);
       // TODO invalid location
       if (loc)
         entry.location = *loc;
@@ -96,9 +98,9 @@ struct CqueryMemberHierarchyInitialHandler
         break;
       }
       if (sym.kind == SymbolKind::Var) {
-        QueryVar& var = db->GetVar(sym);
-        if (var.def && var.def->type)
-          out.result = BuildInitial(db, working_files, *var.def->type);
+        const QueryVar::Def* def = db->GetVar(sym).AnyDef();
+        if (def && def->type)
+          out.result = BuildInitial(db, working_files, *def->type);
         break;
       }
     }
diff --git a/src/messages/cquery_random.cc b/src/messages/cquery_random.cc
index e4664591..c0963720 100644
--- a/src/messages/cquery_random.cc
+++ b/src/messages/cquery_random.cc
@@ -55,7 +55,7 @@ struct CqueryRandomHandler : BaseMessageHandler<Ipc_CqueryRandom> {
         sym2id[syms.back()] = n++;
       }
     for (RawId i = 0; i < db->vars.size(); i++)
-      if (db->vars[i].def) {
+      if (db->vars[i].AnyDef()) {
         syms.push_back(SymbolIdx{Id<void>(i), SymbolKind::Var});
         sym2id[syms.back()] = n++;
       }
@@ -70,14 +70,14 @@ struct CqueryRandomHandler : BaseMessageHandler<Ipc_CqueryRandom> {
     };
     n = 0;
     for (QueryFunc& func : db->funcs)
-      if (func.def) {
+      if (func.AnyDef()) {
         add(func.declarations, kDeclWeight);
         add(func.uses, 1);
         Add(sym2id, adj, func.derived, n);
         n++;
       }
     for (QueryType& type : db->types)
-      if (type.def) {
+      if (type.AnyDef()) {
         add(type.uses, 1);
         Add(sym2id, adj, type.instances, n);
         Add(sym2id, adj, type.def->funcs, n);
@@ -86,7 +86,7 @@ struct CqueryRandomHandler : BaseMessageHandler<Ipc_CqueryRandom> {
         n++;
       }
     for (QueryVar& var : db->vars)
-      if (var.def) {
+      if (var.AnyDef()) {
         add(var.declarations, kDeclWeight);
         add(var.uses, 1);
         n++;
diff --git a/src/messages/cquery_vars.cc b/src/messages/cquery_vars.cc
index d36eca86..68fab4c5 100644
--- a/src/messages/cquery_vars.cc
+++ b/src/messages/cquery_vars.cc
@@ -30,10 +30,10 @@ struct CqueryVarsHandler : BaseMessageHandler<Ipc_CqueryVars> {
         default:
           break;
         case SymbolKind::Var: {
-          QueryVar& var = db->GetVar(sym);
-          if (!var.def || !var.def->type)
+          const QueryVar::Def* def = db->GetVar(sym).AnyDef();
+          if (!def || !def->type)
             continue;
-          id = *var.def->type;
+          id = *def->type;
         }
         // fallthrough
         case SymbolKind::Type: {
diff --git a/src/messages/text_document_code_action.cc b/src/messages/text_document_code_action.cc
index f7f0d6dc..f4a32e49 100644
--- a/src/messages/text_document_code_action.cc
+++ b/src/messages/text_document_code_action.cc
@@ -80,11 +80,11 @@ optional<QueryFileId> GetImplementationFile(QueryDatabase* db,
         break;
       }
       case SymbolKind::Var: {
-        QueryVar& var = db->GetVar(sym);
+        const QueryVar::Def* def = db->GetVar(sym).AnyDef();
         // Note: we ignore the definition if it is in the same file (ie,
         // possibly a header).
-        if (var.def && var.def->extent) {
-          QueryFileId t = var.def->extent->file;
+        if (def && def->extent) {
+          QueryFileId t = def->extent->file;
           if (t != file_id)
             return t;
         }
diff --git a/src/messages/text_document_code_lens.cc b/src/messages/text_document_code_lens.cc
index dfcb9727..b7ccf04a 100644
--- a/src/messages/text_document_code_lens.cc
+++ b/src/messages/text_document_code_lens.cc
@@ -247,16 +247,14 @@ struct TextDocumentCodeLensHandler
         }
         case SymbolKind::Var: {
           QueryVar& var = db->GetVar(sym);
-          if (!var.def)
-            continue;
-
-          if (var.def->is_local() && !config->codeLensOnLocalVariables)
+          const QueryVar::Def* def = var.AnyDef();
+          if (!def || (def->is_local() && !config->codeLensOnLocalVariables))
             continue;
 
           bool force_display = true;
           // Do not show 0 refs on macro with no uses, as it is most likely
           // a header guard.
-          if (var.def->is_macro())
+          if (def->is_macro())
             force_display = false;
 
           AddCodeLens("ref", "refs", &common, OffsetStartColumn(sym, 0),
diff --git a/src/messages/text_document_definition.cc b/src/messages/text_document_definition.cc
index ff9e8b24..b46e590f 100644
--- a/src/messages/text_document_definition.cc
+++ b/src/messages/text_document_definition.cc
@@ -37,10 +37,10 @@ std::vector<Use> GetGotoDefinitionTargets(QueryDatabase* db,
     case SymbolKind::Var: {
       std::vector<Use> ret =
           GetDeclarationsOfSymbolForGotoDefinition(db, sym);
-      QueryVar& var = db->GetVar(sym);
-      if (var.def && var.def->type) {
+      QueryVar::Def* def = db->GetVar(sym).AnyDef();
+      if (def && def->type) {
         std::vector<Use> types = GetDeclarationsOfSymbolForGotoDefinition(
-            db, SymbolIdx{*var.def->type, SymbolKind::Type});
+            db, SymbolIdx{*def->type, SymbolKind::Type});
         ret.insert(ret.end(), types.begin(), types.end());
       }
       return ret;
diff --git a/src/messages/text_document_hover.cc b/src/messages/text_document_hover.cc
index 6d7b1961..9af5f077 100644
--- a/src/messages/text_document_hover.cc
+++ b/src/messages/text_document_hover.cc
@@ -9,30 +9,27 @@ std::pair<std::string_view, std::string_view> GetCommentsAndHover(
     SymbolRef sym) {
   switch (sym.kind) {
     case SymbolKind::Type: {
-      QueryType& type = db->GetType(sym);
-      if (type.def)
-        return {type.def->comments,
-                !type.def->hover.empty()
-                    ? std::string_view(type.def->hover)
-                    : std::string_view(type.def->detailed_name)};
+      if (const auto* def = db->GetType(sym).AnyDef()) {
+        return {def->comments, !def->hover.empty()
+                                   ? std::string_view(def->hover)
+                                   : std::string_view(def->detailed_name)};
+      }
       break;
     }
     case SymbolKind::Func: {
-      QueryFunc& func = db->GetFunc(sym);
-      if (func.def)
-        return {func.def->comments,
-                !func.def->hover.empty()
-                    ? std::string_view(func.def->hover)
-                    : std::string_view(func.def->detailed_name)};
+      if (const auto* def = db->GetFunc(sym).AnyDef()) {
+        return {def->comments, !def->hover.empty()
+                                   ? std::string_view(def->hover)
+                                   : std::string_view(def->detailed_name)};
+      }
       break;
     }
     case SymbolKind::Var: {
-      QueryVar& var = db->GetVar(sym);
-      if (var.def)
-        return {var.def->comments,
-                !var.def->hover.empty()
-                    ? std::string_view(var.def->hover)
-                    : std::string_view(var.def->detailed_name)};
+      if (const auto* def = db->GetVar(sym).AnyDef()) {
+        return {def->comments, !def->hover.empty()
+                                   ? std::string_view(def->hover)
+                                   : std::string_view(def->detailed_name)};
+      }
       break;
     }
     case SymbolKind::File:
diff --git a/src/query.cc b/src/query.cc
index f985c41d..a9529c74 100644
--- a/src/query.cc
+++ b/src/query.cc
@@ -772,8 +772,7 @@ void QueryDatabase::RemoveUsrs(SymbolKind usr_kind,
         QueryVar& var = vars[usr_to_var[usr].id];
         if (var.symbol_idx)
           symbols[var.symbol_idx->id].kind = SymbolKind::Invalid;
-        //var.def = QueryVar::Def();
-        var.def = nullopt;
+        var.def.clear();
       }
       break;
     }
@@ -895,10 +894,10 @@ void QueryDatabase::ImportOrUpdate(std::vector<QueryVar::DefUpdate>&& updates) {
     QueryVar& existing = vars[it->second.id];
 
     // Keep the existing definition if it is higher quality.
-    if (!(existing.def && existing.def->spell &&
+    if (!(existing.AnyDef() && existing.AnyDef()->spell &&
           !def.value.spell)) {
-      existing.def = std::move(def.value);
-      if (!def.value.is_local())
+      existing.def.push_front(std::move(def.value));
+      if (!existing.def.front().is_local())
         UpdateSymbols(&existing.symbol_idx, SymbolKind::Var, it->second);
     }
   }
@@ -924,19 +923,19 @@ std::string_view QueryDatabase::GetSymbolDetailedName(RawId symbol_idx) const {
         return files[idx].def->path;
       break;
     case SymbolKind::Func:
-      if (funcs[idx].def) {
-        auto& def = funcs[idx].def;
+      if (const auto* def = funcs[idx].AnyDef()) {
+        // Assume the part after short_name is not needed.
         return std::string_view(def->detailed_name)
             .substr(0, def->short_name_offset + def->short_name_size);
       }
       break;
     case SymbolKind::Type:
-      if (types[idx].def)
-        return types[idx].def->detailed_name;
+      if (const auto* def = types[idx].AnyDef())
+        return def->detailed_name;
       break;
     case SymbolKind::Var:
-      if (vars[idx].def)
-        return vars[idx].def->detailed_name;
+      if (const auto* def = vars[idx].AnyDef())
+        return def->detailed_name;
       break;
   }
   return "";
@@ -952,16 +951,16 @@ std::string_view QueryDatabase::GetSymbolShortName(RawId symbol_idx) const {
         return files[idx].def->path;
       break;
     case SymbolKind::Func:
-      if (funcs[idx].def)
-        return funcs[idx].def->ShortName();
+      if (const auto* def = funcs[idx].AnyDef())
+        return def->ShortName();
       break;
     case SymbolKind::Type:
-      if (types[idx].def)
-        return types[idx].def->ShortName();
+      if (const auto* def = types[idx].AnyDef())
+        return def->ShortName();
       break;
     case SymbolKind::Var:
-      if (vars[idx].def)
-        return vars[idx].def->ShortName();
+      if (const auto* def = vars[idx].AnyDef())
+        return def->ShortName();
       break;
   }
   return "";
diff --git a/src/query.h b/src/query.h
index 75f5b084..8a852152 100644
--- a/src/query.h
+++ b/src/query.h
@@ -5,6 +5,7 @@
 
 #include <sparsepp/spp.h>
 
+#include <forward_list>
 #include <functional>
 
 struct QueryFile;
@@ -145,6 +146,8 @@ struct QueryType {
   std::vector<Use> uses;
 
   explicit QueryType(const Usr& usr) : usr(usr) {}
+  const Def* AnyDef() const { return def ? &*def : nullptr; }
+  Def* AnyDef() { return def ? &*def : nullptr; }
 };
 
 struct QueryFunc {
@@ -162,6 +165,8 @@ struct QueryFunc {
   std::vector<Use> uses;
 
   explicit QueryFunc(const Usr& usr) : usr(usr) {}
+  const Def* AnyDef() const { return def ? &*def : nullptr; }
+  Def* AnyDef() { return def ? &*def : nullptr; }
 };
 
 struct QueryVar {
@@ -172,11 +177,19 @@ struct QueryVar {
 
   Usr usr;
   Maybe<Id<void>> symbol_idx;
-  optional<Def> def;
+  std::forward_list<Def> def;
   std::vector<Use> declarations;
   std::vector<Use> uses;
 
   explicit QueryVar(const Usr& usr) : usr(usr) {}
+  const Def* AnyDef() const {
+    if (def.empty()) return nullptr;
+    return &def.front();
+  }
+  Def* AnyDef() {
+    if (def.empty()) return nullptr;
+    return &def.front();
+  }
 };
 
 struct IndexUpdate {
@@ -297,21 +310,21 @@ struct QueryDatabase {
       case SymbolKind::File:
         return QueryFileId(ref.id);
       case SymbolKind::Func: {
-        QueryFunc& file = funcs[ref.id.id];
-        if (file.def)
-          return file.def->file;
+        const QueryFunc::Def* def = funcs[ref.id.id].AnyDef();
+        if (def)
+          return def->file;
         break;
       }
       case SymbolKind::Type: {
-        QueryType& type = types[ref.id.id];
-        if (type.def)
-          return type.def->file;
+        const QueryType::Def* def = types[ref.id.id].AnyDef();
+        if (def)
+          return def->file;
         break;
       }
       case SymbolKind::Var: {
-        QueryVar& var = vars[ref.id.id];
-        if (var.def)
-          return var.def->file;
+        const QueryVar::Def* def = vars[ref.id.id].AnyDef();
+        if (def)
+          return def->file;
         break;
       }
     }
diff --git a/src/query_utils.cc b/src/query_utils.cc
index f30a87b0..a6289aad 100644
--- a/src/query_utils.cc
+++ b/src/query_utils.cc
@@ -34,9 +34,9 @@ Maybe<Use> GetDefinitionSpellingOfSymbol(QueryDatabase* db,
       break;
     }
     case SymbolKind::Var: {
-      QueryVar& var = db->GetVar(sym);
-      if (var.def)
-        return var.def->spell;
+      const QueryVar::Def* def = db->GetVar(sym).AnyDef();
+      if (def)
+        return def->spell;
       break;
     }
     case SymbolKind::File:
@@ -63,9 +63,9 @@ Maybe<Use> GetDefinitionExtentOfSymbol(QueryDatabase* db, SymbolIdx sym) {
       break;
     }
     case SymbolKind::Var: {
-      QueryVar& var = db->GetVar(sym);
-      if (var.def)
-        return var.def->extent;
+      const QueryVar::Def* def = db->GetVar(sym).AnyDef();
+      if (def)
+        return def->extent;
       break;
     }
     case SymbolKind::File:
@@ -97,9 +97,9 @@ Maybe<QueryFileId> GetDeclarationFileForSymbol(QueryDatabase* db,
       break;
     }
     case SymbolKind::Var: {
-      QueryVar& var = db->GetVar(sym);
-      if (var.def)
-        return var.def->file;
+      const QueryVar::Def* def = db->GetVar(sym).AnyDef();
+      if (def)
+        return def->file;
       break;
     }
     case SymbolKind::File:
@@ -143,8 +143,9 @@ std::vector<Use> ToUses(QueryDatabase* db, const std::vector<QueryVarId>& ids) {
   ret.reserve(ids.size());
   for (auto id : ids) {
     QueryVar& var = db->vars[id.id];
-    if (var.def && var.def->spell)
-      ret.push_back(*var.def->spell);
+    QueryVar::Def* def = var.AnyDef();
+    if (def && def->spell)
+      ret.push_back(*def->spell);
     else if (var.declarations.size())
       ret.push_back(var.declarations[0]);
   }
@@ -158,16 +159,20 @@ std::vector<Use> GetUsesOfSymbol(QueryDatabase* db,
     case SymbolKind::Type: {
       QueryType& type = db->GetType(sym);
       std::vector<Use> ret = type.uses;
-      if (include_decl && type.def && type.def->spell)
-        ret.push_back(*type.def->spell);
+      if (include_decl) {
+        const QueryType::Def* def = type.AnyDef();
+        if (def && def->spell)
+          ret.push_back(*def->spell);
+      }
       return ret;
     }
     case SymbolKind::Func: {
       QueryFunc& func = db->GetFunc(sym);
       std::vector<Use> ret = func.uses;
       if (include_decl) {
-        if (func.def && func.def->spell)
-          ret.push_back(*func.def->spell);
+        const QueryFunc::Def* def = func.AnyDef();
+        if (def && def->spell)
+          ret.push_back(*def->spell);
         AddRange(&ret, func.declarations);
       }
       return ret;
@@ -176,8 +181,9 @@ std::vector<Use> GetUsesOfSymbol(QueryDatabase* db,
       QueryVar& var = db->GetVar(sym);
       std::vector<Use> ret = var.uses;
       if (include_decl) {
-        if (var.def && var.def->spell)
-          ret.push_back(*var.def->spell);
+        const QueryVar::Def* def = var.AnyDef();
+        if (def && def->spell)
+          ret.push_back(*def->spell);
         ret.insert(ret.end(), var.declarations.begin(), var.declarations.end());
       }
       return ret;
@@ -393,21 +399,21 @@ optional<lsLocationEx> GetLsLocationEx(QueryDatabase* db,
     default:
       break;
     case SymbolKind::Func: {
-      QueryFunc& func = db->GetFunc(use);
-      if (func.def)
-        ret.containerName = std::string_view(func.def->detailed_name);
+      const QueryFunc::Def* def = db->GetFunc(use).AnyDef();
+      if (def)
+        ret.containerName = std::string_view(def->detailed_name);
       break;
     }
     case SymbolKind::Type: {
-      QueryType& type = db->GetType(use);
-      if (type.def)
-        ret.containerName = std::string_view(type.def->detailed_name);
+      const QueryType::Def* def = db->GetType(use).AnyDef();
+      if (def)
+        ret.containerName = std::string_view(def->detailed_name);
       break;
     }
     case SymbolKind::Var: {
-      QueryVar& var = db->GetVar(use);
-      if (var.def)
-        ret.containerName = std::string_view(var.def->detailed_name);
+      const QueryVar::Def* def = db->GetVar(use).AnyDef();
+      if (def)
+        ret.containerName = std::string_view(def->detailed_name);
       break;
     }
     }
@@ -492,17 +498,17 @@ optional<lsSymbolInformation> GetSymbolInfo(QueryDatabase* db,
       return info;
     }
     case SymbolKind::Var: {
-      QueryVar& var = db->GetVar(sym);
-      if (!var.def)
+      const QueryVar::Def* def = db->GetVar(sym).AnyDef();
+      if (!def)
         break;
 
       lsSymbolInformation info;
       if (use_short_name)
-        info.name = var.def->ShortName();
+        info.name = def->ShortName();
       else
-        info.name = var.def->detailed_name;
-      info.containerName = var.def->detailed_name;
-      switch (var.def->kind) {
+        info.name = def->detailed_name;
+      info.containerName = def->detailed_name;
+      switch (def->kind) {
         default:
           info.kind = lsSymbolKind::Variable;
           break;
diff --git a/src/query_utils.h b/src/query_utils.h
index 8f865541..eefaa0cf 100644
--- a/src/query_utils.h
+++ b/src/query_utils.h
@@ -69,15 +69,15 @@ void EachWithGen(std::vector<Q>& collection, Id<Q> x, Fn fn) {
   Q& obj = collection[x.id];
   // FIXME Deprecate optional<Def> def
   //  if (obj.gen == x.gen && obj.def)
-  if (obj.def)
+  if (obj.AnyDef())
     fn(obj);
 }
 
 template <typename Q, typename Fn>
-void EachWithGen(std::vector<Q>& collection, std::vector<Id<Q>>& ids, Fn fn) {
+void EachWithGen(std::vector<Q>& collection, const std::vector<Id<Q>>& ids, Fn fn) {
   for (Id<Q> x : ids) {
     Q& obj = collection[x.id];
-    if (obj.def) // FIXME Deprecate optional<Def> def
+    if (obj.AnyDef())
       fn(obj);
   }
 }