diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index 65e84be39b9..266fbc23399 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -68,7 +68,7 @@
  * GUC parameters
  */
 int			WalWriterDelay = 200;
-int			WalWriterFlushAfter = 128;
+int			WalWriterFlushAfter = DEFAULT_WAL_WRITER_FLUSH_AFTER;
 
 /*
  * Number of do-nothing loops before lengthening the delay time, and the
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index efd59a47cf7..8abf9bb6446 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2780,7 +2780,7 @@ struct config_int ConfigureNamesInt[] =
 			GUC_UNIT_XBLOCKS
 		},
 		&WalWriterFlushAfter,
-		(1024 * 1024) / XLOG_BLCKSZ, 0, INT_MAX,
+		DEFAULT_WAL_WRITER_FLUSH_AFTER, 0, INT_MAX,
 		NULL, NULL, NULL
 	},
 
diff --git a/src/include/postmaster/walwriter.h b/src/include/postmaster/walwriter.h
index 22281a97ba0..6eba7ad79cf 100644
--- a/src/include/postmaster/walwriter.h
+++ b/src/include/postmaster/walwriter.h
@@ -12,6 +12,8 @@
 #ifndef _WALWRITER_H
 #define _WALWRITER_H
 
+#define DEFAULT_WAL_WRITER_FLUSH_AFTER ((1024 * 1024) / XLOG_BLCKSZ)
+
 /* GUC options */
 extern PGDLLIMPORT int WalWriterDelay;
 extern PGDLLIMPORT int WalWriterFlushAfter;