diff --git a/src/backend/replication/logical/origin.c b/src/backend/replication/logical/origin.c
index cc2b513..02bcd85 100644
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -533,7 +533,7 @@ CheckPointReplicationOrigin(void)
 	 * no other backend can perform this at the same time, we're protected by
 	 * CheckpointLock.
 	 */
-	tmpfd = OpenTransientFile((char *) tmppath,
+	tmpfd = OpenTransientFile(tmppath,
 							  O_CREAT | O_EXCL | O_WRONLY | PG_BINARY,
 							  S_IRUSR | S_IWUSR);
 	if (tmpfd < 0)
@@ -644,7 +644,7 @@ StartupReplicationOrigin(void)
 
 	elog(DEBUG2, "starting up replication origin progress state");
 
-	fd = OpenTransientFile((char *) path, O_RDONLY | PG_BINARY, 0);
+	fd = OpenTransientFile(path, O_RDONLY | PG_BINARY, 0);
 
 	/*
 	 * might have had max_replication_slots == 0 last run, or we just brought
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 03143f1..c2819be 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -597,7 +597,7 @@ durable_rename(const char *oldfile, const char *newfile, int elevel)
 	if (fsync_fname_ext(oldfile, false, false, elevel) != 0)
 		return -1;
 
-	fd = OpenTransientFile((char *) newfile, PG_BINARY | O_RDWR, 0);
+	fd = OpenTransientFile(newfile, PG_BINARY | O_RDWR, 0);
 	if (fd < 0)
 	{
 		if (errno != ENOENT)
@@ -2953,7 +2953,7 @@ pre_sync_fname(const char *fname, bool isdir, int elevel)
 	if (isdir)
 		return;
 
-	fd = OpenTransientFile((char *) fname, O_RDONLY | PG_BINARY, 0);
+	fd = OpenTransientFile(fname, O_RDONLY | PG_BINARY, 0);
 
 	if (fd < 0)
 	{
@@ -3013,7 +3013,7 @@ fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
 	else
 		flags |= O_RDONLY;
 
-	fd = OpenTransientFile((char *) fname, flags, 0);
+	fd = OpenTransientFile(fname, flags, 0);
 
 	/*
 	 * Some OSs don't allow us to open directories at all (Windows returns
diff --git a/src/include/storage/fd.h b/src/include/storage/fd.h
index cbc2224..7a1e33b 100644
--- a/src/include/storage/fd.h
+++ b/src/include/storage/fd.h
@@ -46,7 +46,7 @@
  * FileSeek uses the standard UNIX lseek(2) flags.
  */
 
-typedef char *FileName;
+typedef const char *FileName;
 
 typedef int File;