diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 3acafaad5a8..98651b473a9 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3638,7 +3638,7 @@ static struct config_real ConfigureNamesReal[] =
 		},
 		&CheckPointCompletionTarget,
 		0.5, 0.0, 1.0,
-		NULL, NULL, NULL
+		NULL, assign_checkpoint_completion_target, NULL
 	},
 
 	{