diff --git a/src/backend/utils/adt/jsonpath_scan.l b/src/backend/utils/adt/jsonpath_scan.l
index ea824bae73e..948f379e767 100644
--- a/src/backend/utils/adt/jsonpath_scan.l
+++ b/src/backend/utils/adt/jsonpath_scan.l
@@ -37,7 +37,7 @@ static char *scanbuf;
 static int	scanbuflen;
 
 static void addstring(bool init, char *s, int l);
-static void addchar(bool init, char s);
+static void addchar(bool init, char c);
 static enum yytokentype checkKeyword(void);
 static void parseUnicode(char *s, int l);
 static void parseHexChar(char *s);
diff --git a/src/bin/pgbench/pgbench.h b/src/bin/pgbench/pgbench.h
index 40903bc1618..a8a0dcaa307 100644
--- a/src/bin/pgbench/pgbench.h
+++ b/src/bin/pgbench/pgbench.h
@@ -141,9 +141,9 @@ struct PgBenchExprList
 extern PgBenchExpr *expr_parse_result;
 
 extern int	expr_yyparse(yyscan_t yyscanner);
-extern int	expr_yylex(union YYSTYPE *lvalp, yyscan_t yyscanner);
-extern void expr_yyerror(yyscan_t yyscanner, const char *str) pg_attribute_noreturn();
-extern void expr_yyerror_more(yyscan_t yyscanner, const char *str,
+extern int	expr_yylex(union YYSTYPE *yylval_param, yyscan_t yyscanner);
+extern void expr_yyerror(yyscan_t yyscanner, const char *message) pg_attribute_noreturn();
+extern void expr_yyerror_more(yyscan_t yyscanner, const char *message,
 							  const char *more) pg_attribute_noreturn();
 extern bool expr_lex_one_word(PsqlScanState state, PQExpBuffer word_buf,
 							  int *offset);
diff --git a/src/include/bootstrap/bootstrap.h b/src/include/bootstrap/bootstrap.h
index 89f5b01b31a..c825adc4037 100644
--- a/src/include/bootstrap/bootstrap.h
+++ b/src/include/bootstrap/bootstrap.h
@@ -57,6 +57,6 @@ extern void boot_get_type_io_data(Oid typid,
 extern int	boot_yyparse(void);
 
 extern int	boot_yylex(void);
-extern void boot_yyerror(const char *str) pg_attribute_noreturn();
+extern void boot_yyerror(const char *message) pg_attribute_noreturn();
 
 #endif							/* BOOTSTRAP_H */
diff --git a/src/include/parser/scanner.h b/src/include/parser/scanner.h
index 0843481517e..e775d96c742 100644
--- a/src/include/parser/scanner.h
+++ b/src/include/parser/scanner.h
@@ -138,7 +138,7 @@ extern core_yyscan_t scanner_init(const char *str,
 								  const ScanKeywordList *keywordlist,
 								  const uint16 *keyword_tokens);
 extern void scanner_finish(core_yyscan_t yyscanner);
-extern int	core_yylex(core_YYSTYPE *lvalp, YYLTYPE *llocp,
+extern int	core_yylex(core_YYSTYPE *yylval_param, YYLTYPE *yylloc_param,
 					   core_yyscan_t yyscanner);
 extern int	scanner_errposition(int location, core_yyscan_t yyscanner);
 extern void setup_scanner_errposition_callback(ScannerCallbackState *scbstate,
diff --git a/src/include/replication/walsender_private.h b/src/include/replication/walsender_private.h
index cb4da76a896..7897c74589e 100644
--- a/src/include/replication/walsender_private.h
+++ b/src/include/replication/walsender_private.h
@@ -118,7 +118,7 @@ extern void WalSndSetState(WalSndState state);
  */
 extern int	replication_yyparse(void);
 extern int	replication_yylex(void);
-extern void replication_yyerror(const char *str) pg_attribute_noreturn();
+extern void replication_yyerror(const char *message) pg_attribute_noreturn();
 extern void replication_scanner_init(const char *str);
 extern void replication_scanner_finish(void);
 extern bool replication_scanner_is_replication_command(void);
diff --git a/src/test/isolation/isolationtester.h b/src/test/isolation/isolationtester.h
index e00bc6b816b..77134b03ba7 100644
--- a/src/test/isolation/isolationtester.h
+++ b/src/test/isolation/isolationtester.h
@@ -88,6 +88,6 @@ extern TestSpec parseresult;
 extern int	spec_yyparse(void);
 
 extern int	spec_yylex(void);
-extern void spec_yyerror(const char *str);
+extern void spec_yyerror(const char *message);
 
 #endif							/* ISOLATIONTESTER_H */