diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index 273465d..a4e9bea 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -278,7 +278,7 @@
   call assert_equal(2, index(0zDEADBEEF, 0xBE))
   call assert_equal(-1, index(0zDEADBEEF, 0))
   call assert_equal(2, index(0z11111111, 0x11, 2))
-  call assert_equal(3, index(0z11110111, 0x11, 2))
+  call assert_equal(3, 0z11110111->index(0x11, 2))
   call assert_equal(2, index(0z11111111, 0x11, -2))
   call assert_equal(3, index(0z11110111, 0x11, -2))