diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index e9f542cfed..bc3df736e5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2651,7 +2651,7 @@ static struct config_int ConfigureNamesInt[] =
 #ifdef USE_PREFETCH
 		1, 0, MAX_IO_CONCURRENCY,
 #else
-		0, 0, 0,
+		0, 0, MAX_IO_CONCURRENCY,
 #endif
 		check_effective_io_concurrency, assign_effective_io_concurrency, NULL
 	},
@@ -10709,6 +10709,11 @@ check_effective_io_concurrency(int *newval, void **extra, GucSource source)
 	else
 		return false;
 #else
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("effective_io_concurrency can only be set to 0 on platforms which lack posix_advise()");
+		return false;
+	}
 	return true;
 #endif							/* USE_PREFETCH */
 }