diff --git a/R/boot.R b/R/boot.R
index edb40593..13cff66b 100644
--- a/R/boot.R
+++ b/R/boot.R
@@ -76,7 +76,7 @@ bootstraps <-
       if (length(strata) == 0) strata <- NULL
     }
 
-    strata_check(strata, data)
+    check_strata(strata, data)
 
     split_objs <-
       boot_splits(
diff --git a/R/initial_validation_split.R b/R/initial_validation_split.R
index 4d89ebc6..95f8f884 100644
--- a/R/initial_validation_split.R
+++ b/R/initial_validation_split.R
@@ -68,7 +68,7 @@ initial_validation_split <- function(data,
       strata <- NULL
     }
   }
-  strata_check(strata, data)
+  check_strata(strata, data)
 
   split_train <- mc_cv(
       data = data,
@@ -209,7 +209,7 @@ group_initial_validation_split <- function(data,
       strata <- NULL
     }
   }
-  strata_check(strata, data)
+  check_strata(strata, data)
 
   if (missing(strata)) {
     split_train <- group_mc_cv(
diff --git a/R/mc.R b/R/mc.R
index 12d80677..35ebfd49 100644
--- a/R/mc.R
+++ b/R/mc.R
@@ -58,7 +58,7 @@ mc_cv <- function(data, prop = 3 / 4, times = 25,
     if (length(strata) == 0) strata <- NULL
   }
 
-  strata_check(strata, data)
+  check_strata(strata, data)
 
   split_objs <-
     mc_splits(
diff --git a/R/misc.R b/R/misc.R
index bb202a39..ab174bae 100644
--- a/R/misc.R
+++ b/R/misc.R
@@ -98,16 +98,17 @@ add_class <- function(x, cls) {
   x
 }
 
-strata_check <- function(strata, data) {
+check_strata <- function(strata, data, call = caller_env()) {
+  check_string(strata, allow_null = TRUE, call = call)
+
   if (!is.null(strata)) {
-    if (!is.character(strata) | length(strata) != 1) {
-      cli_abort("{.arg strata} should be a single name or character value.")
-    }
     if (inherits(data[, strata], "Surv")) {
-      cli_abort("{.arg strata} cannot be a {.cls Surv} object. Use the time or event variable directly.")
-    }
-    if (!(strata %in% names(data))) {
-      cli_abort("{strata} is not in {.arg data}.")
+      cli_abort(c(
+        "{.field strata} cannot be a {.cls Surv} object.",
+        "i" = "Use the time or event variable directly."
+        ),
+        call = call
+      )
     }
   }
   invisible(NULL)
diff --git a/R/validation_split.R b/R/validation_split.R
index 26e5e947..bbe509b1 100644
--- a/R/validation_split.R
+++ b/R/validation_split.R
@@ -67,7 +67,7 @@ validation_split <- function(data, prop = 3 / 4,
     }
   }
 
-  strata_check(strata, data)
+  check_strata(strata, data)
 
   split_objs <-
     mc_splits(
diff --git a/R/vfold.R b/R/vfold.R
index 2a2ac616..faded51e 100644
--- a/R/vfold.R
+++ b/R/vfold.R
@@ -71,7 +71,7 @@ vfold_cv <- function(data, v = 10, repeats = 1,
     if (length(strata) == 0) strata <- NULL
   }
 
-  strata_check(strata, data)
+  check_strata(strata, data)
   check_repeats(repeats)
 
   if (repeats == 1) {
diff --git a/tests/testthat/_snaps/boot.md b/tests/testthat/_snaps/boot.md
index 442c72ca..8119cead 100644
--- a/tests/testthat/_snaps/boot.md
+++ b/tests/testthat/_snaps/boot.md
@@ -26,8 +26,8 @@
     Code
       bootstraps(warpbreaks, strata = c("tension", "wool"))
     Condition
-      Error in `strata_check()`:
-      ! `strata` should be a single name or character value.
+      Error in `bootstraps()`:
+      ! `strata` must be a single string or `NULL`, not a character vector.
 
 ---
 
diff --git a/tests/testthat/_snaps/make_strata.md b/tests/testthat/_snaps/make_strata.md
index 35a70cfb..2c5ff244 100644
--- a/tests/testthat/_snaps/make_strata.md
+++ b/tests/testthat/_snaps/make_strata.md
@@ -67,8 +67,9 @@
 # don't stratify on Surv objects
 
     Code
-      strata_check("surv", df)
+      check_strata("surv", df)
     Condition
-      Error in `strata_check()`:
-      ! `strata` cannot be a <Surv> object. Use the time or event variable directly.
+      Error:
+      ! strata cannot be a <Surv> object.
+      i Use the time or event variable directly.
 
diff --git a/tests/testthat/_snaps/mc.md b/tests/testthat/_snaps/mc.md
index 22446560..f7ab64cf 100644
--- a/tests/testthat/_snaps/mc.md
+++ b/tests/testthat/_snaps/mc.md
@@ -12,8 +12,8 @@
     Code
       mc_cv(warpbreaks, strata = c("tension", "wool"))
     Condition
-      Error in `strata_check()`:
-      ! `strata` should be a single name or character value.
+      Error in `mc_cv()`:
+      ! `strata` must be a single string or `NULL`, not a character vector.
 
 # printing
 
diff --git a/tests/testthat/_snaps/validation_split.md b/tests/testthat/_snaps/validation_split.md
index a9215489..692f1440 100644
--- a/tests/testthat/_snaps/validation_split.md
+++ b/tests/testthat/_snaps/validation_split.md
@@ -91,8 +91,8 @@
     Code
       validation_split(warpbreaks, strata = c("tension", "wool"))
     Condition
-      Error in `strata_check()`:
-      ! `strata` should be a single name or character value.
+      Error in `validation_split()`:
+      ! `strata` must be a single string or `NULL`, not a character vector.
 
 # printing
 
diff --git a/tests/testthat/_snaps/vfold.md b/tests/testthat/_snaps/vfold.md
index d590cc6b..add53300 100644
--- a/tests/testthat/_snaps/vfold.md
+++ b/tests/testthat/_snaps/vfold.md
@@ -7,7 +7,7 @@
       Stratifying groups that make up 1% of the data may be statistically risky.
       * Consider increasing `pool` to at least 0.1
 
-# bad args
+# strata arg is checked
 
     Code
       vfold_cv(iris, strata = iris$Species)
@@ -21,11 +21,28 @@
     Code
       vfold_cv(iris, strata = c("Species", "Sepal.Width"))
     Condition
-      Error in `strata_check()`:
-      ! `strata` should be a single name or character value.
+      Error in `vfold_cv()`:
+      ! `strata` must be a single string or `NULL`, not a character vector.
+
+---
+
+    Code
+      vfold_cv(iris, strata = NA)
+    Condition
+      Error in `vfold_cv()`:
+      ! Selections can't have missing values.
 
 ---
 
+    Code
+      vfold_cv(dat, strata = b)
+    Condition
+      Error in `vfold_cv()`:
+      ! strata cannot be a <Surv> object.
+      i Use the time or event variable directly.
+
+# bad args
+
     Code
       vfold_cv(iris, v = -500)
     Condition
diff --git a/tests/testthat/test-make_strata.R b/tests/testthat/test-make_strata.R
index 3704783b..08ace53f 100644
--- a/tests/testthat/test-make_strata.R
+++ b/tests/testthat/test-make_strata.R
@@ -39,7 +39,7 @@ test_that("bad data", {
 
 
 
-# strata_check() ----------------------------------------------------------
+# check_strata() ----------------------------------------------------------
 
 test_that("don't stratify on Surv objects", {
   df <- data.frame(
@@ -58,6 +58,6 @@ test_that("don't stratify on Surv objects", {
   )
 
   expect_snapshot(error = TRUE, {
-    strata_check("surv", df)
+    check_strata("surv", df)
   })
 })
diff --git a/tests/testthat/test-vfold.R b/tests/testthat/test-vfold.R
index 9b81bae1..f6e7bd1f 100644
--- a/tests/testthat/test-vfold.R
+++ b/tests/testthat/test-vfold.R
@@ -74,14 +74,37 @@ test_that("strata", {
   )
 })
 
-
-test_that("bad args", {
+test_that("strata arg is checked", {
   expect_snapshot(error = TRUE, {
     vfold_cv(iris, strata = iris$Species)
   })
+
+  # errors from `check_strata()`
   expect_snapshot(error = TRUE, {
     vfold_cv(iris, strata = c("Species", "Sepal.Width"))
   })
+
+  expect_snapshot(error = TRUE, {
+    vfold_cv(iris, strata = NA)
+  })
+  
+  # make Surv object without a dependeny on the survival package
+  surv_obj <- structure(
+    c(306, 455, 1010, 210, 883, 1, 1, 0, 1, 1), 
+    dim = c(5L, 2L), 
+    dimnames = list(NULL, c("time", "status")),
+    type = "right", 
+    class = "Surv"
+  )
+  dat <- data.frame(a = 1:5)
+  # add Surv object like this for older R versions (<= 4.2.3)
+  dat$b <- surv_obj
+  expect_snapshot(error = TRUE, {
+    vfold_cv(dat, strata = b)
+  })
+})
+
+test_that("bad args", {
   expect_snapshot(error = TRUE, {
     vfold_cv(iris, v = -500)
   })