diff --git a/R/class_branch.R b/R/class_branch.R
index f0f15d66..d5f8b5ee 100644
--- a/R/class_branch.R
+++ b/R/class_branch.R
@@ -8,7 +8,10 @@ branch_init <- function(
   store = NULL,
   index = NULL
 ) {
-  deps <- setdiff(unique(c(deps_parent, deps_child)), settings$dimensions)
+  deps <- setdiff_chr(
+    x = unique.default(c(deps_parent, deps_child)),
+    y = settings$dimensions
+  )
   branch_new(
     name = name,
     command = command,
diff --git a/R/utils_data.R b/R/utils_data.R
index 2993d6bc..a06ec5b2 100644
--- a/R/utils_data.R
+++ b/R/utils_data.R
@@ -46,6 +46,10 @@ set_names <- function(x, names) {
   x
 }
 
+setdiff_chr <- function(x, y) {
+  x[!duplicated.default(x) & (match(x, y, 0L) == 0L)]
+}
+
 sort_chr <- function(x) {
   old_locale <- Sys.getlocale(category = "LC_COLLATE")
   on.exit(Sys.setlocale(category = "LC_COLLATE", locale = old_locale))
diff --git a/tests/testthat/test-utils_data.R b/tests/testthat/test-utils_data.R
index 554a5cce..14463a63 100644
--- a/tests/testthat/test-utils_data.R
+++ b/tests/testthat/test-utils_data.R
@@ -55,6 +55,12 @@ tar_test("supported_args()", {
   )
 })
 
+tar_test("setdiff_chr()", {
+  expect_equal(setdiff_chr("x", character(0L)), "x")
+  expect_equal(setdiff_chr(character(0L), "x"), character(0L))
+  expect_equal(setdiff(c("d", "a", "b"), "a"), c("d", "b"))
+})
+
 tar_test("sort_chr()", {
   expect_equal(sort_chr(c("a", "b")), c("a", "b"))
   expect_equal(sort_chr(character(0L)), character(0L))