diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index 69b3504..3eff715 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -271,6 +271,7 @@
 
 " filter() item in blob
 func Test_blob_filter()
+  call assert_equal(test_null_blob(), filter(test_null_blob(), '0'))
   call assert_equal(0z, filter(0zDEADBEEF, '0'))
   call assert_equal(0zADBEEF, filter(0zDEADBEEF, 'v:val != 0xDE'))
   call assert_equal(0zDEADEF, filter(0zDEADBEEF, 'v:val != 0xBE'))
diff --git a/src/testdir/test_filter_map.vim b/src/testdir/test_filter_map.vim
index 249c32f..e6587c2 100644
--- a/src/testdir/test_filter_map.vim
+++ b/src/testdir/test_filter_map.vim
@@ -98,10 +98,10 @@
   call assert_fails("let l = filter([1, 2, 3], '{}')", 'E728:')
   call assert_fails("let l = filter({'k' : 10}, '{}')", 'E728:')
   call assert_fails("let l = filter([1, 2], {})", 'E731:')
-  call assert_equal(0, filter(test_null_list(), 0))
-  call assert_equal(0, filter(test_null_dict(), 0))
-  call assert_equal(0, map(test_null_list(), '"> " .. v:val'))
-  call assert_equal(0, map(test_null_dict(), '"> " .. v:val'))
+  call assert_equal(test_null_list(), filter(test_null_list(), 0))
+  call assert_equal(test_null_dict(), filter(test_null_dict(), 0))
+  call assert_equal(test_null_list(), map(test_null_list(), '"> " .. v:val'))
+  call assert_equal(test_null_dict(), map(test_null_dict(), '"> " .. v:val'))
   call assert_equal([1, 2, 3], filter([1, 2, 3], test_null_function()))
   call assert_fails("let l = filter([1, 2], function('min'))", 'E118:')
   call assert_equal([1, 2, 3], filter([1, 2, 3], test_null_partial()))