diff --git a/src/backend/replication/Makefile b/src/backend/replication/Makefile
index da8bcf0471..562b55fbaa 100644
--- a/src/backend/replication/Makefile
+++ b/src/backend/replication/Makefile
@@ -24,10 +24,9 @@ include $(top_srcdir)/src/backend/common.mk
 # repl_scanner is compiled as part of repl_gram
 repl_gram.o: repl_scanner.c
 
-# syncrep_scanner is complied as part of syncrep_gram
+# syncrep_scanner is compiled as part of syncrep_gram
 syncrep_gram.o: syncrep_scanner.c
-syncrep_scanner.c: FLEXFLAGS = -CF -p -i
-syncrep_scanner.c: FLEX_NO_BACKUP=yes
 
 # repl_gram.c, repl_scanner.c, syncrep_gram.c and syncrep_scanner.c
 # are in the distribution tarball, so they are not cleaned here.
+# (Our parent Makefile takes care of them during maintainer-clean.)
diff --git a/src/backend/replication/syncrep_scanner.l b/src/backend/replication/syncrep_scanner.l
index 7baf1b68d1..d1d1b26a48 100644
--- a/src/backend/replication/syncrep_scanner.l
+++ b/src/backend/replication/syncrep_scanner.l
@@ -64,8 +64,10 @@ xdinside		[^"]+
 %%
 {space}+	{ /* ignore */ }
 
-ANY		{ return ANY; }
-FIRST		{ return FIRST; }
+	/* brute-force case insensitivity is safer than relying on flex -i */
+
+[Aa][Nn][Yy]			{ return ANY; }
+[Ff][Ii][Rr][Ss][Tt]	{ return FIRST; }
 
 {xdstart}	{
 				initStringInfo(&xdbuf);