diff --git a/userland/testbin/badcall/bad_sbrk.c b/userland/testbin/badcall/bad_sbrk.c
index 8849db8..dc4f351 100644
--- a/userland/testbin/badcall/bad_sbrk.c
+++ b/userland/testbin/badcall/bad_sbrk.c
@@ -74,7 +74,7 @@ static
 int
 sbrk_bigpos(void)
 {
-	return enforce_sbrk(4096*1024*256, "huge positive", ENOMEM);
+	return enforce_sbrk(1024*1024*1024 + (1024*1024*1024 - 4096*17), "huge positive", ENOMEM);
 }
 
 static