diff --git a/src/V3PreLex.l b/src/V3PreLex.l
index 81dcd763f..e32ee7c0c 100644
--- a/src/V3PreLex.l
+++ b/src/V3PreLex.l
@@ -524,7 +524,7 @@ again:
         }
     }
     if (debug() >= 10) {
-        cout << "-  pp::inputToLex  got=" << got << " '" << string(buf, got) << "'" << endl;
+        cout << "-  pp::inputToLex  got=" << got << " '" << std::string{buf, got} << "'" << endl;
     }
     return got;
 }
@@ -567,7 +567,7 @@ string V3PreLex::endOfStream(bool& againr) {
         // Final shutdown phase for a stream, we can finally change the
         // current fileline to the new stream
         curStreamp()->m_termState = 0;
-        FileLine* filelinep = curFilelinep();
+        FileLine* const filelinep = curFilelinep();
         delete curStreamp();
         m_streampStack.pop();  // Must work as size>1; EOF is entry 0
         if (curStreamp()->m_eof) {
@@ -590,7 +590,7 @@ string V3PreLex::endOfStream(bool& againr) {
 void V3PreLex::initFirstBuffer(FileLine* filelinep) {
     // Called from constructor to make first buffer
     // yy_create_buffer also sets yy_fill_buffer=1 so reads from YY_INPUT
-    VPreStream* streamp = new VPreStream(filelinep, this);
+    VPreStream* const streamp = new VPreStream{filelinep, this};
     streamp->m_eof = true;
     m_streampStack.push(streamp);
     //
@@ -606,7 +606,7 @@ void V3PreLex::scanNewFile(FileLine* filelinep) {
         yyerrorf("Recursive `define or other nested inclusion");
         curStreamp()->m_eof = true;  // Fake it to stop recursion
     } else {
-        VPreStream* streamp = new VPreStream(filelinep, this);
+        VPreStream* const streamp = new VPreStream{filelinep, this};
         m_tokFilelinep = curFilelinep();
         streamp->m_file = true;
         scanSwitchStream(streamp);
@@ -615,7 +615,7 @@ void V3PreLex::scanNewFile(FileLine* filelinep) {
 
 void V3PreLex::scanBytes(const string& str) {
     // Note buffers also appended in ::scanBytesBack
-    // Not "m_buffers.push_front(string(strp,len))" as we need a `define
+    // Not "m_buffers.push_front(string{strp,len})" as we need a `define
     // to take effect immediately, in the middle of the current buffer
     // Also we don't use scan_bytes that would set yy_fill_buffer
     // which would force Flex to bypass our YY_INPUT routine.
@@ -625,7 +625,7 @@ void V3PreLex::scanBytes(const string& str) {
         yyerrorf("Recursive `define or other nested inclusion");
         curStreamp()->m_eof = true;  // Fake it to stop recursion
     } else {
-        VPreStream* streamp = new VPreStream(curFilelinep(), this);
+        VPreStream* const streamp = new VPreStream{curFilelinep(), this};
         streamp->m_buffers.push_front(str);
         scanSwitchStream(streamp);
     }
@@ -649,7 +649,7 @@ string V3PreLex::currentUnreadChars() {
     ssize_t left = (yy_n_chars - (yy_c_buf_p - currentBuffer()->yy_ch_buf));
     if (left > 0) {  // left may be -1 at EOS
         *(yy_c_buf_p) = (yy_hold_char);
-        return string(yy_c_buf_p, left);
+        return std::string(yy_c_buf_p, left);  // () narrowing conversion
     } else {
         return "";
     }
@@ -689,7 +689,7 @@ void V3PreLex::dumpStack() {
     dumpSummary();
     std::stack<VPreStream*> tmpstack = LEXP->m_streampStack;
     while (!tmpstack.empty()) {
-        VPreStream* streamp = tmpstack.top();
+        const VPreStream* const streamp = tmpstack.top();
         cout << "-    bufferStack[" << cvtToHex(streamp) << "]: "
              << " at=" << streamp->m_curFilelinep << " nBuf=" << streamp->m_buffers.size()
              << " size0=" << (streamp->m_buffers.empty() ? 0 : streamp->m_buffers.front().length())
diff --git a/src/verilog.l b/src/verilog.l
index d000c3fad..3c831abea 100644
--- a/src/verilog.l
+++ b/src/verilog.l
@@ -60,9 +60,9 @@
 //======================================================================
 
 static double lexParseDouble(FileLine* fl, const char* textp, size_t length) {
-    string text = std::string(textp, length);
+    const string text = std::string{textp, length};
     bool success = false;
-    double d = VString::parseDouble(text, &success);
+    const double d = VString::parseDouble(text, &success);
     if (!success) fl->v3error("Syntax error parsing real: '" << textp << "'");
     return d;
 }
@@ -608,7 +608,7 @@ vnum    {vnum1}|{vnum2}|{vnum3}|{vnum4}|{vnum5}
 
   /* Default PLI rule */
 <V95,V01NC,V01C,V05,VA5,S05,S09,S12,S17,SAX>{
-  "$"[a-zA-Z_$][a-zA-Z0-9_$]*   { string str (yytext, yyleng);
+  "$"[a-zA-Z_$][a-zA-Z0-9_$]*   { const string str (yytext, yyleng);
                                   yylval.strp = PARSEP->newString(AstNode::encodeName(str));
                                   FL; return yaD_PLI;
                                 }
@@ -861,10 +861,10 @@ vnum    {vnum1}|{vnum2}|{vnum3}|{vnum4}|{vnum5}
   /* Identifiers and numbers */
 <V95,V01NC,V01C,V05,VA5,S05,S09,S12,S17,SAX,VLT>{
   {escid}               { FL; yylval.strp = PARSEP->newString
-                                (AstNode::encodeName(string(yytext+1)));  // +1 to skip the backslash
+                                  (AstNode::encodeName(std::string{yytext+1}));  // +1 to skip the backslash
                           return yaID__LEX;
                         }
-  {id}                  { FL; yylval.strp = PARSEP->newString(AstNode::encodeName(string(yytext)));
+  {id}                  { FL; yylval.strp = PARSEP->newString(AstNode::encodeName(std::string{yytext}));
                           return yaID__LEX;
                         }
   \"[^\"\\]*\"          { FL; yylval.strp = PARSEP->newString(yytext+1, yyleng-2);
@@ -875,10 +875,10 @@ vnum    {vnum1}|{vnum2}|{vnum3}|{vnum4}|{vnum5}
                           /* "# 1'b0" is a delay value so must lex as "#" "1" "'b0" */
                           if (PARSEP->lexPrevToken()=='#') {
                               int shortlen = 0;
-                              while (isdigit(yytext[shortlen])) shortlen++;
+                              while (isdigit(yytext[shortlen])) ++shortlen;
                               if (shortlen) {
                                   // Push rest past numbers for later parse
-                                  PARSEP->lexUnputString(yytext+shortlen, yyleng-shortlen);
+                                  PARSEP->lexUnputString(yytext + shortlen, yyleng - shortlen);
                                   // Return is stuff before the tick
                                   yyleng = shortlen;
                                   yytext[yyleng] = '\0';