diff --git a/R/aaa_models.R b/R/aaa_models.R
index 112d5b225..2a5f6017e 100644
--- a/R/aaa_models.R
+++ b/R/aaa_models.R
@@ -127,21 +127,27 @@ check_model_doesnt_exist <- function(model) {
 }
 
 check_mode_val <- function(mode) {
-  if (rlang::is_missing(mode) || length(mode) != 1 || !is.character(mode))
+  if (rlang::is_missing(mode) || length(mode) != 1 || !is.character(mode)) {
     rlang::abort("Please supply a character string for a mode (e.g. `'regression'`).")
+  }
   invisible(NULL)
 }
 
 # check if class and mode are compatible
 check_spec_mode_val <- function(cls, mode) {
   spec_modes <- rlang::env_get(get_model_env(), paste0(cls, "_modes"))
-  if (!(mode %in% spec_modes))
-    rlang::abort(
-      glue::glue(
-        "`mode` should be one of: ",
-        glue::glue_collapse(glue::glue("'{spec_modes}'"), sep = ", ")
-      )
+  compatible_modes <-
+    glue::glue(
+      "`mode` should be one of: ",
+      glue::glue_collapse(glue::glue("'{spec_modes}'"), sep = ", ")
     )
+
+  if (is.null(mode)) {
+    rlang::abort(compatible_modes)
+  } else if (!(mode %in% spec_modes)) {
+    rlang::abort(compatible_modes)
+  }
+
   invisible(NULL)
 }
 
diff --git a/R/arguments.R b/R/arguments.R
index 3a4d887b3..ed2b995a7 100644
--- a/R/arguments.R
+++ b/R/arguments.R
@@ -76,17 +76,10 @@ set_args <- function(object, ...) {
 #' @rdname set_args
 #' @export
 set_mode <- function(object, mode) {
-  if (is.null(mode))
-    return(object)
-  mode <- mode[1]
-  if (!(any(all_modes == mode))) {
-    rlang::abort(
-      glue::glue(
-        "`mode` should be one of ",
-        glue::glue_collapse(glue::glue("'{all_modes}'"), sep = ", ")
-      )
-    )
+  if (rlang::is_missing(mode)) {
+    mode <- NULL
   }
+  mode <- mode[1]
   check_spec_mode_val(class(object)[1], mode)
   object$mode <- mode
   object
diff --git a/R/engines.R b/R/engines.R
index 913cf8a1e..1babb0186 100644
--- a/R/engines.R
+++ b/R/engines.R
@@ -15,6 +15,10 @@ check_engine <- function(object) {
   if (is.null(object$engine)) {
     object$engine <- avail_eng[1]
     rlang::warn(glue::glue("`engine` was NULL and updated to be `{object$engine}`"))
+  } else {
+    if (!is.character(object$engine) | length(object$engine) != 1) {
+      rlang::abort("`engine` should be a single character value.")
+    }
   }
   if (!(object$engine %in% avail_eng)) {
     rlang::abort(
@@ -91,18 +95,20 @@ set_engine <- function(object, engine, ...) {
   if (!inherits(object, "model_spec")) {
     rlang::abort("`object` should have class 'model_spec'.")
   }
-  if (!is.character(engine) | length(engine) != 1)
-    rlang::abort("`engine` should be a single character value.")
-  if (engine == "liquidSVM") {
+
+  if (rlang::is_missing(engine)) {
+    engine <- NULL
+  }
+  object$engine <- engine
+  object <- check_engine(object)
+
+  if (object$engine == "liquidSVM") {
     lifecycle::deprecate_soft(
       "0.1.6",
       "set_engine(engine = 'cannot be liquidSVM')",
       details = "The liquidSVM package is no longer available on CRAN.")
   }
 
-  object$engine <- engine
-  object <- check_engine(object)
-
   new_model_spec(
     cls = class(object)[1],
     args = object$args,
diff --git a/tests/testthat/test_mars.R b/tests/testthat/test_mars.R
index 63fa17e57..ca5b3e650 100644
--- a/tests/testthat/test_mars.R
+++ b/tests/testthat/test_mars.R
@@ -111,8 +111,8 @@ test_that('updating', {
 })
 
 test_that('bad input', {
+  expect_warning(translate(mars(mode = "regression") %>% set_engine()))
   expect_error(translate(mars() %>% set_engine("wat?")))
-  expect_error(translate(mars(mode = "regression") %>% set_engine()))
   expect_error(translate(mars(formula = y ~ x)))
 })
 
diff --git a/tests/testthat/test_multinom_reg.R b/tests/testthat/test_multinom_reg.R
index 6a1b0037d..81118532a 100644
--- a/tests/testthat/test_multinom_reg.R
+++ b/tests/testthat/test_multinom_reg.R
@@ -109,7 +109,7 @@ test_that('updating', {
 
 test_that('bad input', {
   expect_error(multinom_reg(mode = "regression"))
-  expect_error(translate(multinom_reg() %>% set_engine("wat?")))
-  expect_error(translate(multinom_reg() %>% set_engine()))
-  expect_warning(translate(multinom_reg(penalty = 0.01) %>% set_engine("glmnet", x = hpc[,1:3], y = hpc$class)))
+  expect_error(translate(multinom_reg(penalty = 0.1) %>% set_engine("wat?")))
+  expect_warning(multinom_reg(penalty = 0.1) %>% set_engine())
+  expect_warning(translate(multinom_reg(penalty = 0.1) %>% set_engine("glmnet", x = hpc[,1:3], y = hpc$class)))
 })
diff --git a/tests/testthat/test_nearest_neighbor.R b/tests/testthat/test_nearest_neighbor.R
index 29b3f7f35..a550fa4ba 100644
--- a/tests/testthat/test_nearest_neighbor.R
+++ b/tests/testthat/test_nearest_neighbor.R
@@ -122,5 +122,5 @@ test_that('updating', {
 
 test_that('bad input', {
   expect_error(nearest_neighbor(mode = "reallyunknown"))
-  expect_error(translate(nearest_neighbor() %>% set_engine( NULL)))
+  expect_warning(nearest_neighbor() %>% set_engine( NULL))
 })
diff --git a/tests/testthat/test_nullmodel.R b/tests/testthat/test_nullmodel.R
index aaf77532a..9a5af12bf 100644
--- a/tests/testthat/test_nullmodel.R
+++ b/tests/testthat/test_nullmodel.R
@@ -32,8 +32,8 @@ test_that('engine arguments', {
 })
 
 test_that('bad input', {
+  expect_warning(translate(null_model(mode = "regression") %>% set_engine()))
   expect_error(translate(null_model() %>% set_engine("wat?")))
-  expect_error(translate(null_model(mode = "regression") %>% set_engine()))
   expect_error(translate(null_model(formula = y ~ x)))
   expect_warning(
     translate(
diff --git a/tests/testthat/test_rand_forest.R b/tests/testthat/test_rand_forest.R
index 1be3aa7e8..b8dbf361f 100644
--- a/tests/testthat/test_rand_forest.R
+++ b/tests/testthat/test_rand_forest.R
@@ -192,9 +192,9 @@ test_that('updating', {
 })
 
 test_that('bad input', {
+  expect_warning(translate(rand_forest(mode = "classification") %>% set_engine(NULL)))
   expect_error(rand_forest(mode = "time series"))
   expect_error(translate(rand_forest(mode = "classification") %>% set_engine("wat?")))
-  expect_error(translate(rand_forest(mode = "classification") %>% set_engine(NULL)))
   expect_error(translate(rand_forest(mode = "classification", ytest = 2)))
 })
 
diff --git a/tests/testthat/test_surv_reg.R b/tests/testthat/test_surv_reg.R
index 424f48a9b..1947bed41 100644
--- a/tests/testthat/test_surv_reg.R
+++ b/tests/testthat/test_surv_reg.R
@@ -85,7 +85,7 @@ test_that('bad input', {
 
   expect_error(surv_reg(mode = ", classification"))
   expect_error(translate(surv_reg() %>% set_engine("wat")))
-  expect_error(translate(surv_reg() %>% set_engine(NULL)))
+  expect_warning(translate(surv_reg() %>% set_engine(NULL)))
 })
 
 test_that("deprecation warning", {
diff --git a/tests/testthat/test_svm_linear.R b/tests/testthat/test_svm_linear.R
index 24d4ced4a..f878aa95f 100644
--- a/tests/testthat/test_svm_linear.R
+++ b/tests/testthat/test_svm_linear.R
@@ -104,8 +104,8 @@ test_that('updating', {
 })
 
 test_that('bad input', {
+  expect_warning(translate(svm_linear(mode = "regression") %>% set_engine( NULL)))
   expect_error(svm_linear(mode = "reallyunknown"))
-  expect_error(translate(svm_linear(mode = "regression") %>% set_engine( NULL)))
   expect_error(translate(svm_linear(mode = "regression") %>% set_engine("LiblineaR", type = 3)))
   expect_error(translate(svm_linear(mode = "classification") %>% set_engine("LiblineaR", type = 11)))
 })
diff --git a/tests/testthat/test_svm_liquidsvm.R b/tests/testthat/test_svm_liquidsvm.R
index 373ff4c12..2a966b8e9 100644
--- a/tests/testthat/test_svm_liquidsvm.R
+++ b/tests/testthat/test_svm_liquidsvm.R
@@ -77,5 +77,5 @@ test_that('updating', {
 
 test_that('bad input', {
   expect_error(svm_rbf(mode = "reallyunknown"))
-  expect_error(translate(svm_rbf() %>% set_engine( NULL)))
+  expect_warning(svm_rbf() %>% set_engine( NULL))
 })
diff --git a/tests/testthat/test_svm_poly.R b/tests/testthat/test_svm_poly.R
index fef562ccd..fd403560f 100644
--- a/tests/testthat/test_svm_poly.R
+++ b/tests/testthat/test_svm_poly.R
@@ -106,7 +106,7 @@ test_that('updating', {
 
 test_that('bad input', {
   expect_error(svm_poly(mode = "reallyunknown"))
-  expect_error(translate(svm_poly() %>% set_engine( NULL)))
+  expect_warning(svm_poly() %>% set_engine(NULL))
 })
 
 # ------------------------------------------------------------------------------
diff --git a/tests/testthat/test_svm_rbf.R b/tests/testthat/test_svm_rbf.R
index 059754fbf..9541f1792 100644
--- a/tests/testthat/test_svm_rbf.R
+++ b/tests/testthat/test_svm_rbf.R
@@ -87,7 +87,7 @@ test_that('updating', {
 
 test_that('bad input', {
   expect_error(svm_rbf(mode = "reallyunknown"))
-  expect_error(translate(svm_rbf(mode = "regression") %>% set_engine( NULL)))
+  expect_warning(translate(svm_rbf(mode = "regression") %>% set_engine( NULL)))
 })
 
 # ------------------------------------------------------------------------------