diff --git a/src/log_surgeon/LALR1Parser.tpp b/src/log_surgeon/LALR1Parser.tpp
index 02f38cd8..f356bd6f 100644
--- a/src/log_surgeon/LALR1Parser.tpp
+++ b/src/log_surgeon/LALR1Parser.tpp
@@ -88,18 +88,17 @@ auto LALR1Parser<NfaStateType, DfaStateType>::add_token_chain(
         std::string const& chain
 ) -> void {
     assert(chain.size() > 1);
-    std::unique_ptr<finite_automata::RegexASTLiteral<NfaStateType>> first_char_rule
+    auto first_char_rule
             = std::make_unique<finite_automata::RegexASTLiteral<NfaStateType>>(chain[0]);
-    std::unique_ptr<finite_automata::RegexASTLiteral<NfaStateType>> second_char_rule
+    auto second_char_rule
             = std::make_unique<finite_automata::RegexASTLiteral<NfaStateType>>(chain[1]);
-    std::unique_ptr<finite_automata::RegexASTCat<NfaStateType>> rule_chain
-            = std::make_unique<finite_automata::RegexASTCat<NfaStateType>>(
-                    std::move(first_char_rule),
-                    std::move(second_char_rule)
-            );
+    auto rule_chain = std::make_unique<finite_automata::RegexASTCat<NfaStateType>>(
+            std::move(first_char_rule),
+            std::move(second_char_rule)
+    );
     for (uint32_t i = 2; i < chain.size(); i++) {
-        char next_char = chain[i];
-        std::unique_ptr<finite_automata::RegexASTLiteral<NfaStateType>> next_char_rule
+        auto next_char = chain[i];
+        auto next_char_rule
                 = std::make_unique<finite_automata::RegexASTLiteral<NfaStateType>>(next_char);
         rule_chain = std::make_unique<finite_automata::RegexASTCat<NfaStateType>>(
                 std::move(rule_chain),
diff --git a/src/log_surgeon/Lexer.tpp b/src/log_surgeon/Lexer.tpp
index b1ff9f76..04c2f50d 100644
--- a/src/log_surgeon/Lexer.tpp
+++ b/src/log_surgeon/Lexer.tpp
@@ -65,9 +65,9 @@ auto Lexer<NfaStateType, DfaStateType>::scan(ParserInputBuffer& input_buffer, To
         m_type_ids = nullptr;
     }
     while (true) {
-        uint32_t prev_byte_buf_pos = input_buffer.storage().pos();
-        unsigned char next_char{utf8::cCharErr};
-        if (ErrorCode err = input_buffer.get_next_character(next_char); ErrorCode::Success != err) {
+        auto prev_byte_buf_pos = input_buffer.storage().pos();
+        auto next_char{utf8::cCharErr};
+        if (auto const err = input_buffer.get_next_character(next_char); ErrorCode::Success != err) {
             m_asked_for_more_data = true;
             m_prev_state = state;
             return err;
@@ -80,7 +80,7 @@ auto Lexer<NfaStateType, DfaStateType>::scan(ParserInputBuffer& input_buffer, To
             m_match_pos = prev_byte_buf_pos;
             m_match_line = m_line;
         }
-        DfaStateType* next = state->next(next_char);
+        auto* next = state->next(next_char);
         if (next_char == '\n') {
             m_line++;
             if (m_has_delimiters && !m_match) {
diff --git a/src/log_surgeon/LogEvent.cpp b/src/log_surgeon/LogEvent.cpp
index 709e62ce..8a3deead 100644
--- a/src/log_surgeon/LogEvent.cpp
+++ b/src/log_surgeon/LogEvent.cpp
@@ -42,7 +42,7 @@ auto LogEventView::reset() -> void {
         start = 1;
     }
     for (uint32_t i = start; i < m_log_output_buffer->pos(); i++) {
-        Token& token = m_log_output_buffer->get_mutable_token(i);
+        auto& token = m_log_output_buffer->get_mutable_token(i);
         raw_log += token.to_string_view();
     }
     return raw_log;
@@ -51,7 +51,7 @@ auto LogEventView::reset() -> void {
 auto LogEventView::get_logtype() const -> std::string {
     std::string logtype;
     for (uint32_t i = 1; i < m_log_output_buffer->pos(); i++) {
-        Token& token = m_log_output_buffer->get_mutable_token(i);
+        auto& token = m_log_output_buffer->get_mutable_token(i);
         if (token.m_type_ids_ptr->at(0) == (uint32_t)SymbolId::TokenUncaughtString) {
             logtype += token.to_string_view();
         } else {
diff --git a/src/log_surgeon/Schema.cpp b/src/log_surgeon/Schema.cpp
index e2008b18..dd4b0869 100644
--- a/src/log_surgeon/Schema.cpp
+++ b/src/log_surgeon/Schema.cpp
@@ -11,7 +11,7 @@ Schema::Schema(std::string const& schema_file_path)
         : m_schema_ast{SchemaParser::try_schema_file(schema_file_path)} {}
 
 auto Schema::add_variable(std::string_view const var_schema, int const priority) const -> void {
-    std::unique_ptr<SchemaAST> const schema_ast = SchemaParser::try_schema_string(var_schema);
+    auto const schema_ast = SchemaParser::try_schema_string(var_schema);
     m_schema_ast->add_schema_var(std::move(schema_ast->m_schema_vars[0]), priority);
 }
 }  // namespace log_surgeon