diff --git a/NEWS.md b/NEWS.md
index 3963a8c..a69dcb9 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # finetune (development version)
 
+* Improved error message from `tune_sim_anneal()` when values in the supplied `param_info` do not encompass all values evaluated in the `initial` grid. This most often happens when a user mistakenly supplies different parameter sets to the function that generated the initial results and `tune_sim_anneal()`.
+
 * Fixed bug where `tune_sim_anneal()` would fail when supplied parameters needing finalization. The function will now finalize needed parameter ranges internally (#39).
 
 * Fixed bug where packages specified in `control_race(pkgs)` were not actually loaded in `tune_race_anova()` (#74).
diff --git a/R/sim_anneal_helpers.R b/R/sim_anneal_helpers.R
index 494804b..fe5b00a 100644
--- a/R/sim_anneal_helpers.R
+++ b/R/sim_anneal_helpers.R
@@ -144,11 +144,30 @@ random_real_neighbor <- function(current, hist_values, pset, retain = 1,
 
 encode_set_backwards <- function(x, pset, ...) {
   pset <- pset[pset$id %in% names(x), ]
+  mapply(check_backwards_encode, pset$object, x, pset$id,
+         SIMPLIFY = FALSE, USE.NAMES = FALSE)
   new_vals <- purrr::map2(pset$object, x, dials::encode_unit, direction = "backward")
   names(new_vals) <- names(x)
   tibble::as_tibble(new_vals)
 }
 
+check_backwards_encode <- function(x, value, id) {
+  if (!dials::has_unknowns(x)) {
+    compl <- value[!is.na(value)]
+    if (any(compl < 0) | any(compl > 1)) {
+      cli::cli_abort(c(
+        "!" = "The range for parameter {.val {noquote(id)}} used when \\
+               generating initial results isn't compatible with the range \\
+               supplied in {.arg param_info}.",
+        "i" = "Possible values of parameters in {.arg param_info} should \\
+               encompass all values evaluated in the initial grid."
+        ),
+        call = rlang::call2("tune_sim_anneal()")
+      )
+    }
+  }
+}
+
 sample_by_distance <- function(candidates, existing, retain, pset) {
   if (nrow(existing) > 0) {
     existing <- tune::encode_set(existing, pset, as_matrix = TRUE)
diff --git a/tests/testthat/_snaps/sa-overall.md b/tests/testthat/_snaps/sa-overall.md
index 0149e8d..86bc3f0 100644
--- a/tests/testthat/_snaps/sa-overall.md
+++ b/tests/testthat/_snaps/sa-overall.md
@@ -239,3 +239,18 @@
       9 - discard suboptimal roc_auc=0.84525 (+/-0.007793)
       10 ( ) accept suboptimal  roc_auc=0.84383 (+/-0.00773)
 
+# incompatible parameter objects
+
+    Code
+      res <- tune_sim_anneal(car_wflow, param_info = parameter_set_with_smaller_range,
+        resamples = car_folds, initial = tune_res_with_bigger_range, iter = 2)
+    Message
+      Optimizing rmse
+      
+    Condition
+      Error in `tune_sim_anneal()`:
+      ! The range for parameter mtry used when generating initial results isn't compatible with the range supplied in `param_info`.
+      i Possible values of parameters in `param_info` should encompass all values evaluated in the initial grid.
+    Message
+      x Optimization stopped prematurely; returning current results.
+
diff --git a/tests/testthat/test-sa-overall.R b/tests/testthat/test-sa-overall.R
index 83af21f..d6751b0 100644
--- a/tests/testthat/test-sa-overall.R
+++ b/tests/testthat/test-sa-overall.R
@@ -127,6 +127,56 @@ test_that("unfinalized parameters", {
   })
 })
 
+test_that("incompatible parameter objects", {
+  skip_on_cran()
+
+  skip_if_not_installed("ranger")
+  skip_if_not_installed("modeldata")
+  skip_if_not_installed("rsample")
+
+  rf_spec <- parsnip::rand_forest(mode = "regression", mtry = tune::tune())
+
+  set.seed(1)
+  grid_with_bigger_range <-
+    dials::grid_latin_hypercube(dials::mtry(range = c(1, 16)))
+
+  set.seed(1)
+  car_folds <- rsample::vfold_cv(car_prices, v = 2)
+
+  car_wflow <- workflows::workflow() %>%
+    workflows::add_formula(Price ~ .) %>%
+    workflows::add_model(rf_spec)
+
+  set.seed(1)
+  tune_res_with_bigger_range <- tune::tune_grid(
+    car_wflow,
+    resamples = car_folds,
+    grid = grid_with_bigger_range
+  )
+
+  set.seed(1)
+  parameter_set_with_smaller_range <-
+    dials::parameters(dials::mtry(range = c(1, 5)))
+
+  scrub_best <- function(lines) {
+    has_best <- grepl("Initial best", lines)
+    lines[has_best] <- ""
+    lines
+  }
+
+  set.seed(1)
+  expect_snapshot(error = TRUE, transform = scrub_best, {
+    res <-
+      tune_sim_anneal(
+        car_wflow,
+        param_info = parameter_set_with_smaller_range,
+        resamples = car_folds,
+        initial = tune_res_with_bigger_range,
+        iter = 2
+      )
+  })
+})
+
 test_that("set event-level", {
   # See issue 40
   skip_if_not_installed("rpart")