diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index 2f558ffea1..d3a2619072 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -99,7 +99,7 @@
 #define LW_VAL_SHARED				1
 
 #define LW_LOCK_MASK				((uint32) ((1 << 25)-1))
-/* Must be greater than MAX_BACKENDS - which is 2^23-1, so we're fine. */
+/* Must be greater than MAX_BACKENDS - which is 2^18-1, so we're fine. */
 #define LW_SHARED_MASK				((uint32) ((1 << 24)-1))
 
 StaticAssertDecl(LW_VAL_EXCLUSIVE > (uint32) MAX_BACKENDS,