diff --git a/tests/testthat/test-checks.R b/tests/testthat/test-checks.R
index e3bc64b5..ed956e79 100644
--- a/tests/testthat/test-checks.R
+++ b/tests/testthat/test-checks.R
@@ -1,15 +1,11 @@
 test_that("Checks work", {
-  expect_error(
-    check_offspring_valid(1),
-    "character string"
-  )
   expect_error(
     check_offspring_func_valid("rrpois"),
-    "does not exist"
+    "not found"
   )
   expect_error(
     check_generation_time_valid("a"),
-    "must be a function"
+    "Must be a function"
   )
   expect_error(
     check_generation_time_valid(function(x) rep("a", 10)),
@@ -17,10 +13,6 @@ test_that("Checks work", {
   )
   expect_error(
     check_generation_time_valid(function(x) 3),
-    "vector of length"
-  )
-  expect_error(
-    check_ntrees_valid(1.1),
-    "less than"
+    "Must have length"
   )
 })
diff --git a/tests/testthat/test-likelihood.R b/tests/testthat/test-likelihood.R
index 96d86735..a30fa1ea 100644
--- a/tests/testthat/test-likelihood.R
+++ b/tests/testthat/test-likelihood.R
@@ -158,7 +158,7 @@ test_that("Errors are thrown", {
       statistic = "size",
       lambda = 0.5
     ),
-    "must be specified as a character string"
+    "Must be of type"
   )
   expect_error(
     likelihood(
diff --git a/tests/testthat/test-simulate.R b/tests/testthat/test-simulate.R
index c73b3828..797ef3df 100644
--- a/tests/testthat/test-simulate.R
+++ b/tests/testthat/test-simulate.R
@@ -87,7 +87,7 @@ test_that("simulate_tree throws errors", {
       statistic = "length",
       lambda = 0.9
     ),
-    "does not exist"
+    "not found"
   )
   expect_error(
     simulate_tree(
@@ -117,7 +117,7 @@ test_that("simulate_tree throws errors", {
       lambda = 0.9,
       generation_time = c(1, 2)
     ),
-    "must be a function"
+    "Must be a function"
   )
   expect_error(
     simulate_tree(
@@ -126,7 +126,7 @@ test_that("simulate_tree throws errors", {
       statistic = "length",
       lambda = 0.9
     ),
-    "character string"
+    "Must be of type"
   )
   expect_error(
     simulate_tree(
@@ -148,7 +148,7 @@ test_that("simulate_summary throws errors", {
       statistic = "length",
       lambda = 0.9
     ),
-    "does not exist"
+    "not found"
   )
   expect_error(
     simulate_summary(
@@ -177,7 +177,7 @@ test_that("simulate_summary throws errors", {
       statistic = "length",
       lambda = 0.9
     ),
-    "character string"
+    "Must be of type"
   )
 })