diff --git a/src/libime/core/constants.h b/src/libime/core/constants.h
index 4dfb0ac..e99f08e 100644
--- a/src/libime/core/constants.h
+++ b/src/libime/core/constants.h
@@ -11,11 +11,11 @@ namespace libime {
 constexpr float DEFAULT_USER_LANGUAGE_MODEL_UNIGRAM_WEIGHT = 3;
 constexpr float DEFAULT_USER_LANGUAGE_MODEL_BIGRAM_WEIGHT = 15;
 constexpr float DEFAULT_LANGUAGE_MODEL_UNKNOWN_PROBABILITY_PENALTY =
-    1 / 60000000.0f;
+    1 / 60000000.0F;
 // -38... is log10(2^-127)
-constexpr float HISTORY_BIGRAM_ALPHA_VALUE = 1.0f;
+constexpr float HISTORY_BIGRAM_ALPHA_VALUE = 1.0F;
 constexpr float MIN_FLOAT_LOG10 = -38.23080944932561;
-constexpr float DEFAULT_USER_LANGUAGE_MODEL_USER_WEIGHT = 0.2f;
+constexpr float DEFAULT_USER_LANGUAGE_MODEL_USER_WEIGHT = 0.2F;
 } // namespace libime
 
 #endif // _FCITX_LIBIME_CORE_CONSTANTS_H_
diff --git a/src/libime/core/datrie.cpp b/src/libime/core/datrie.cpp
index c16f121..c67212f 100644
--- a/src/libime/core/datrie.cpp
+++ b/src/libime/core/datrie.cpp
@@ -18,10 +18,17 @@
 #include <array>
 #include <cassert>
 #include <cmath>
+#include <cstdint>
 #include <cstring>
 #include <fstream>
+#include <ios>
+#include <istream>
 #include <limits>
+#include <ostream>
 #include <stdexcept>
+#include <string>
+#include <string_view>
+#include <tuple>
 #include <vector>
 
 namespace libime {
diff --git a/src/libime/core/decoder.cpp b/src/libime/core/decoder.cpp
index 1f07165..516828c 100644
--- a/src/libime/core/decoder.cpp
+++ b/src/libime/core/decoder.cpp
@@ -7,14 +7,28 @@
 #include "decoder.h"
 #include "languagemodel.h"
 #include "lattice_p.h"
+#include "libime/core/lattice.h"
+#include "libime/core/segmentgraph.h"
 #include "utils.h"
+#include <algorithm>
+#include <boost/container_hash/hash.hpp>
 #include <boost/functional/hash.hpp>
 #include <boost/ptr_container/ptr_vector.hpp>
 #include <boost/range/adaptor/sliced.hpp>
+#include <cassert>
+#include <chrono>
+#include <cstddef>
+#include <fcitx-utils/macros.h>
 #include <limits>
 #include <memory>
 #include <queue>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <unordered_map>
 #include <unordered_set>
+#include <utility>
+#include <vector>
 
 namespace libime {
 
@@ -25,7 +39,7 @@ struct NBestNode {
 
     const LatticeNode *node_;
     // for nbest
-    float gn_ = 0.0f;
+    float gn_ = 0.0F;
     float fn_ = -std::numeric_limits<float>::max();
     std::shared_ptr<NBestNode> next_;
 };
@@ -387,9 +401,10 @@ bool Decoder::decode(Lattice &l, const SegmentGraph &graph, size_t nbest,
 }
 
 LatticeNode *Decoder::createLatticeNodeImpl(
-    const SegmentGraphBase &, const LanguageModelBase *, std::string_view word,
-    WordIndex idx, SegmentGraphPath path, const State &state, float cost,
-    std::unique_ptr<LatticeNodeData>, bool) const {
+    const SegmentGraphBase & /*unused*/, const LanguageModelBase * /*unused*/,
+    std::string_view word, WordIndex idx, SegmentGraphPath path,
+    const State &state, float cost, std::unique_ptr<LatticeNodeData> /*unused*/,
+    bool /*unused*/) const {
     return new LatticeNode(word, idx, std::move(path), state, cost);
 }
 } // namespace libime
diff --git a/src/libime/core/zstdfilter.h b/src/libime/core/zstdfilter.h
index 2ea10a3..982c602 100644
--- a/src/libime/core/zstdfilter.h
+++ b/src/libime/core/zstdfilter.h
@@ -7,11 +7,20 @@
 #ifndef LIBIME_ZSTDFILTER_H
 #define LIBIME_ZSTDFILTER_H
 
+#include <boost/iostreams/categories.hpp>
+#include <boost/iostreams/constants.hpp>
 #include <boost/iostreams/filter/symmetric.hpp>
 #include <boost/iostreams/filtering_streambuf.hpp>
 #include <boost/iostreams/pipeline.hpp>
+#include <boost/throw_exception.hpp>
+#include <cstddef>
+#include <cstring>
 #include <fcitx-utils/log.h>
 #include <fcitx-utils/misc.h>
+#include <ios>
+#include <istream>
+#include <ostream>
+#include <stdexcept>
 #include <zstd.h>
 
 namespace libime {
@@ -41,14 +50,14 @@ enum class ZSTDResult {
 
 class ZSTDFilterBase {
 public:
-    typedef char char_type;
+    using char_type = char;
+    ZSTDFilterBase(const ZSTDFilterBase &) = delete;
 
 protected:
     ZSTDFilterBase() = default;
-    ZSTDFilterBase(const ZSTDFilterBase &) = delete;
     ~ZSTDFilterBase() {}
     void before(const char *&src_begin, const char *src_end, char *&dest_begin,
-                char *dest_end) {
+                const char *dest_end) {
         in_.src = src_begin;
         in_.size = static_cast<size_t>(src_end - src_begin);
         in_.pos = 0;
@@ -56,7 +65,8 @@ class ZSTDFilterBase {
         out_.size = static_cast<size_t>(dest_end - dest_begin);
         out_.pos = 0;
     }
-    void after(const char *&src_begin, char *&dest_begin, bool) {
+    void after(const char *&src_begin, char *&dest_begin,
+               bool /*unused*/) const {
         src_begin = reinterpret_cast<const char *>(in_.src) + in_.pos;
         dest_begin = reinterpret_cast<char *>(out_.dst) + out_.pos;
     }
@@ -95,8 +105,9 @@ class ZSTDCompressorImpl : public ZSTDFilterBase {
     ZSTDResult deflate(bool finish) {
         // Ignore spurious extra calls.
         // Note size > 0 will trigger an error in this case.
-        if (eof_ && in_.size == 0)
+        if (eof_ && in_.size == 0) {
             return ZSTDResult::StreamEnd;
+        }
         size_t result = ZSTD_compressStream(cstream_.get(), &out_, &in_);
         ZSTDError::check(result);
         if (finish) {
@@ -147,12 +158,12 @@ class ZSTDDecompressorImpl : public ZSTDFilterBase {
 struct ZSTDCompressor
     : boost::iostreams::symmetric_filter<details::ZSTDCompressorImpl> {
 private:
-    typedef details::ZSTDCompressorImpl impl_type;
-    typedef symmetric_filter<impl_type> base_type;
+    using impl_type = details::ZSTDCompressorImpl;
+    using base_type = symmetric_filter<impl_type>;
 
 public:
-    typedef typename base_type::char_type char_type;
-    typedef typename base_type::category category;
+    using char_type = typename base_type::char_type;
+    using category = typename base_type::category;
     ZSTDCompressor(std::streamsize buffer_size =
                        boost::iostreams::default_device_buffer_size)
         : base_type(buffer_size) {}
@@ -162,12 +173,12 @@ BOOST_IOSTREAMS_PIPABLE(ZSTDCompressor, 0)
 struct ZSTDDecompressor
     : boost::iostreams::symmetric_filter<details::ZSTDDecompressorImpl> {
 private:
-    typedef details::ZSTDDecompressorImpl impl_type;
-    typedef symmetric_filter<impl_type> base_type;
+    using impl_type = details::ZSTDDecompressorImpl;
+    using base_type = symmetric_filter<impl_type>;
 
 public:
-    typedef typename base_type::char_type char_type;
-    typedef typename base_type::category category;
+    using char_type = typename base_type::char_type;
+    using category = typename base_type::category;
     ZSTDDecompressor(std::streamsize buffer_size =
                          boost::iostreams::default_device_buffer_size)
         : base_type(buffer_size) {}