diff --git a/.Rbuildignore b/.Rbuildignore
index 7205877..ef83f8b 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -9,11 +9,8 @@
 ^\.git$
 ^\.gitignore$
 \.gitkeep$
-^vignettes$
 ^specs$
 ^plans$
-^doc$
-^Meta$
 ^\.gitea$
 ^CLAUDE\.md$
 ^\.superpowers$
diff --git a/tests/testthat/test-config.R b/tests/testthat/test-config.R
index 32cdd83..395fd2a 100644
--- a/tests/testthat/test-config.R
+++ b/tests/testthat/test-config.R
@@ -122,3 +122,12 @@ test_that("LICENSE and LICENSE.md name the same copyright holder", {
   # LICENSE alone, which is how the two came to disagree in the first place.
   expect_match(full, "MIT License", fixed = TRUE)
 })
+
+test_that("vignettes are not excluded from the build", {
+  skip_if_no_source_tree(".Rbuildignore")
+  ignore <- readLines(source_tree_path(".Rbuildignore"), warn = FALSE)
+  expect_false(any(grepl("^\\^vignettes\\$$", ignore)))
+  # The fixture is what lets R CMD check run offline with no credentials on
+  # r-universe and GitHub Actions. It must never be excluded.
+  expect_false(any(grepl("fixture_corpus", ignore, fixed = TRUE)))
+})