diff --git a/src/rewriter/rewriter.cc b/src/rewriter/rewriter.cc
index f310f4a3a..8d924166a 100644
--- a/src/rewriter/rewriter.cc
+++ b/src/rewriter/rewriter.cc
@@ -131,7 +131,7 @@ Rewriter::Rewriter(const engine::Modules &modules) {
   const DataManager &data_manager = modules.GetDataManager();
   const dictionary::DictionaryInterface &dictionary = *modules.GetDictionary();
   const dictionary::PosMatcher &pos_matcher = *modules.GetPosMatcher();
-  const dictionary::PosGroup *pos_group = modules.GetPosGroup();
+  const dictionary::PosGroup &pos_group = *modules.GetPosGroup();
 
 #ifdef MOZC_USER_DICTIONARY_REWRITER
   AddRewriter(std::make_unique<UserDictionaryRewriter>());
@@ -158,7 +158,7 @@ Rewriter::Rewriter(const engine::Modules &modules) {
   if (absl::GetFlag(FLAGS_use_history_rewriter)) {
     AddRewriter(std::make_unique<UserBoundaryHistoryRewriter>());
     AddRewriter(
-        std::make_unique<UserSegmentHistoryRewriter>(&pos_matcher, pos_group));
+        std::make_unique<UserSegmentHistoryRewriter>(pos_matcher, pos_group));
   }
 
 #ifdef MOZC_DATE_REWRITERS
diff --git a/src/rewriter/user_segment_history_rewriter.cc b/src/rewriter/user_segment_history_rewriter.cc
index 7a18d139d..6e0f7db8d 100644
--- a/src/rewriter/user_segment_history_rewriter.cc
+++ b/src/rewriter/user_segment_history_rewriter.cc
@@ -492,10 +492,10 @@ bool UserSegmentHistoryRewriter::SortCandidates(
 }
 
 UserSegmentHistoryRewriter::UserSegmentHistoryRewriter(
-    const PosMatcher *pos_matcher, const PosGroup *pos_group)
+    const PosMatcher &pos_matcher, const PosGroup &pos_group)
     : storage_(std::make_unique<LruStorage>()),
-      pos_matcher_(pos_matcher),
-      pos_group_(pos_group) {
+      pos_matcher_(&pos_matcher),
+      pos_group_(&pos_group) {
   Reload();
 
   CHECK_EQ(sizeof(uint32_t), sizeof(FeatureValue));
diff --git a/src/rewriter/user_segment_history_rewriter.h b/src/rewriter/user_segment_history_rewriter.h
index 556764b06..c9e3a0c98 100644
--- a/src/rewriter/user_segment_history_rewriter.h
+++ b/src/rewriter/user_segment_history_rewriter.h
@@ -49,8 +49,8 @@ namespace mozc {
 
 class UserSegmentHistoryRewriter : public RewriterInterface {
  public:
-  UserSegmentHistoryRewriter(const dictionary::PosMatcher *pos_matcher,
-                             const dictionary::PosGroup *pos_group);
+  UserSegmentHistoryRewriter(const dictionary::PosMatcher &pos_matcher,
+                             const dictionary::PosGroup &pos_group);
 
   bool Rewrite(const ConversionRequest &request,
                Segments *segments) const override;
diff --git a/src/rewriter/user_segment_history_rewriter_test.cc b/src/rewriter/user_segment_history_rewriter_test.cc
index 956f00517..4b331a4db 100644
--- a/src/rewriter/user_segment_history_rewriter_test.cc
+++ b/src/rewriter/user_segment_history_rewriter_test.cc
@@ -167,7 +167,7 @@ class UserSegmentHistoryRewriterTest : public testing::TestWithTempUserProfile {
   }
 
   UserSegmentHistoryRewriter *CreateUserSegmentHistoryRewriter() const {
-    return new UserSegmentHistoryRewriter(&pos_matcher_, pos_group_.get());
+    return new UserSegmentHistoryRewriter(pos_matcher_, *pos_group_);
   }
 
   void SetNumberForm(Config::CharacterForm form) {