diff --git a/contrib/cube/cubescan.l b/contrib/cube/cubescan.l
index dada9178202..bd400e36842 100644
--- a/contrib/cube/cubescan.l
+++ b/contrib/cube/cubescan.l
@@ -4,6 +4,8 @@
  * contrib/cube/cubescan.l
  */
 
+/* LCOV_EXCL_START */
+
 /* No reason to constrain amount of data slurped */
 #define YY_READ_BUF_SIZE 16777216
 
@@ -56,6 +58,8 @@ NaN          [nN][aA][nN]
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 /* result is not used, but Bison expects this signature */
 void
 yyerror(NDBOX **result, const char *message)
diff --git a/contrib/seg/segscan.l b/contrib/seg/segscan.l
index 6db24fdd1f7..5f6595e9eb2 100644
--- a/contrib/seg/segscan.l
+++ b/contrib/seg/segscan.l
@@ -3,6 +3,8 @@
  * A scanner for EMP-style numeric ranges
  */
 
+/* LCOV_EXCL_START */
+
 /* No reason to constrain amount of data slurped */
 #define YY_READ_BUF_SIZE 16777216
 
@@ -51,6 +53,8 @@ float        ({integer}|{real})([eE]{integer})?
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 void
 yyerror(SEG *result, const char *message)
 {
diff --git a/src/backend/bootstrap/bootscanner.l b/src/backend/bootstrap/bootscanner.l
index 51c5e5e3cd6..5465217bc30 100644
--- a/src/backend/bootstrap/bootscanner.l
+++ b/src/backend/bootstrap/bootscanner.l
@@ -38,6 +38,7 @@
 /* Not needed now that this file is compiled as part of bootparse. */
 /* #include "bootparse.h" */
 
+/* LCOV_EXCL_START */
 
 /* Avoid exit() on fatal scanner errors (a bit ugly -- see yy_fatal_error) */
 #undef fprintf
@@ -134,6 +135,8 @@ insert			{ return INSERT_TUPLE; }
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 void
 yyerror(const char *message)
 {
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index 634bfa512f4..6af2199cdc5 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -41,6 +41,9 @@
 }
 
 %{
+
+/* LCOV_EXCL_START */
+
 /* Avoid exit() on fatal scanner errors (a bit ugly -- see yy_fatal_error) */
 #undef fprintf
 #define fprintf(file, fmt, msg)  fprintf_to_ereport(fmt, msg)
@@ -1011,6 +1014,8 @@ other			.
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 /*
  * Arrange access to yyextra for subroutines of the main yylex() function.
  * We expect each subroutine to have a yyscanner parameter.  Rather than
diff --git a/src/backend/replication/repl_scanner.l b/src/backend/replication/repl_scanner.l
index 62bb5288c01..568d55ac953 100644
--- a/src/backend/replication/repl_scanner.l
+++ b/src/backend/replication/repl_scanner.l
@@ -38,6 +38,8 @@ static char *litbufdup(void);
 static void addlit(char *ytext, int yleng);
 static void addlitchar(unsigned char ychar);
 
+/* LCOV_EXCL_START */
+
 %}
 
 %option 8bit
@@ -186,6 +188,7 @@ WAIT				{ return K_WAIT; }
 				}
 %%
 
+/* LCOV_EXCL_STOP */
 
 static void
 startlit(void)
diff --git a/src/backend/replication/syncrep_scanner.l b/src/backend/replication/syncrep_scanner.l
index d1d1b26a480..1fbc936aa6f 100644
--- a/src/backend/replication/syncrep_scanner.l
+++ b/src/backend/replication/syncrep_scanner.l
@@ -32,6 +32,8 @@ static YY_BUFFER_STATE scanbufhandle;
 
 static StringInfoData xdbuf;
 
+/* LCOV_EXCL_START */
+
 %}
 
 %option 8bit
@@ -112,6 +114,7 @@ xdinside		[^"]+
 .			{ return JUNK; }
 %%
 
+/* LCOV_EXCL_STOP */
 
 /* Needs to be here for access to yytext */
 void
diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index f01b814c6ed..3de8e791f21 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -57,6 +57,8 @@ static void record_config_file_error(const char *errmsg,
 static int	GUC_flex_fatal(const char *msg);
 static char *GUC_scanstr(const char *s);
 
+/* LCOV_EXCL_START */
+
 %}
 
 %option 8bit
@@ -107,7 +109,7 @@ STRING			\'([^'\\\n]|\\.|\'\')*\'
 
 %%
 
-
+/* LCOV_EXCL_STOP */
 
 /*
  * Exported function to read and process the configuration file. The
diff --git a/src/bin/pgbench/exprscan.l b/src/bin/pgbench/exprscan.l
index 9bf6d237f57..9f46fb9db88 100644
--- a/src/bin/pgbench/exprscan.l
+++ b/src/bin/pgbench/exprscan.l
@@ -43,6 +43,8 @@ static bool last_was_newline = false;
 extern int	expr_yyget_column(yyscan_t yyscanner);
 extern void expr_yyset_column(int column_no, yyscan_t yyscanner);
 
+/* LCOV_EXCL_START */
+
 %}
 
 /* Except for the prefix, these options should match psqlscan.l */
@@ -190,6 +192,8 @@ continuation	\\{newline}
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 void
 expr_yyerror_more(yyscan_t yyscanner, const char *message, const char *more)
 {
diff --git a/src/bin/psql/psqlscanslash.l b/src/bin/psql/psqlscanslash.l
index 9a53cb3e02b..e3cde04188a 100644
--- a/src/bin/psql/psqlscanslash.l
+++ b/src/bin/psql/psqlscanslash.l
@@ -67,6 +67,8 @@ static void evaluate_backtick(PsqlScanState state);
 extern int	slash_yyget_column(yyscan_t yyscanner);
 extern void slash_yyset_column(int column_no, yyscan_t yyscanner);
 
+/* LCOV_EXCL_START */
+
 %}
 
 /* Except for the prefix, these options should match psqlscan.l */
@@ -468,6 +470,8 @@ other			.
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 /*
  * Scan the command name of a psql backslash command.  This should be called
  * after psql_scan() returns PSCAN_BACKSLASH.  It is assumed that the input
diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l
index 4375142a007..44fcf7ee46e 100644
--- a/src/fe_utils/psqlscan.l
+++ b/src/fe_utils/psqlscan.l
@@ -71,6 +71,8 @@ typedef int YYSTYPE;
 extern int	psql_yyget_column(yyscan_t yyscanner);
 extern void psql_yyset_column(int column_no, yyscan_t yyscanner);
 
+/* LCOV_EXCL_START */
+
 %}
 
 %option reentrant
@@ -899,6 +901,8 @@ other			.
 
 %%
 
+/* LCOV_EXCL_STOP */
+
 /*
  * Create a lexer working state struct.
  *
diff --git a/src/interfaces/ecpg/preproc/pgc.l b/src/interfaces/ecpg/preproc/pgc.l
index fc450f30ab4..e35843ba4ed 100644
--- a/src/interfaces/ecpg/preproc/pgc.l
+++ b/src/interfaces/ecpg/preproc/pgc.l
@@ -79,6 +79,8 @@ static struct _if_value
 	short else_branch;
 } stacked_if_value[MAX_NESTED_IF];
 
+/* LCOV_EXCL_START */
+
 %}
 
 %option 8bit
@@ -1249,7 +1251,11 @@ cppline			{space}*#([^i][A-Za-z]*|{if}|{ifdef}|{ifndef}|{import})((\/\*[^*/]*\*+
 					}
 				}
 <INITIAL>{other}|\n	{ mmfatal(PARSE_ERROR, "internal error: unreachable state; please report this to <pgsql-bugs@postgresql.org>"); }
+
 %%
+
+/* LCOV_EXCL_STOP */
+
 void
 lex_init(void)
 {
diff --git a/src/test/isolation/specscanner.l b/src/test/isolation/specscanner.l
index a9528bda6bb..9c0532c0c5b 100644
--- a/src/test/isolation/specscanner.l
+++ b/src/test/isolation/specscanner.l
@@ -17,6 +17,8 @@ static int litbufpos = 0;
 
 static void addlitchar(char c);
 
+/* LCOV_EXCL_START */
+
 %}
 
 %option 8bit
@@ -93,6 +95,8 @@ teardown		{ return TEARDOWN; }
 				}
 %%
 
+/* LCOV_EXCL_STOP */
+
 static void
 addlitchar(char c)
 {