diff --git a/.gitignore b/.gitignore
index 409c3fb234..92eec21d12 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,6 @@
 **/*.so
 .Rproj.user
 **/tasks.json
+
+# CLion support files
+**/.idea
diff --git a/tests/extendrtests/NAMESPACE b/tests/extendrtests/NAMESPACE
index 81be91f8f3..f804b7780d 100644
--- a/tests/extendrtests/NAMESPACE
+++ b/tests/extendrtests/NAMESPACE
@@ -1,5 +1,4 @@
 # Generated by roxygen2: do not edit by hand
 
-export(add_ints)
-export(hello)
+export(hello_world)
 useDynLib(extendrtests, .registration = TRUE)
diff --git a/tests/extendrtests/R/wrappers.R b/tests/extendrtests/R/wrappers.R
index b3fed5f663..a8e0d0cc5b 100644
--- a/tests/extendrtests/R/wrappers.R
+++ b/tests/extendrtests/R/wrappers.R
@@ -1,15 +1,8 @@
-#' Wrappers for Rust functions.
+#' Wrappers for Rust test functions.
 #' 
-#' Wrappers for Rust functions.
+#' Wrappers for Rust test functions.
 #' @rdname wrappers
 #' @export
-hello <- function() {
-  .Call("wrap__hello")
+hello_world <- function() {
+  .Call("wrap__hello_world")
 }
-
-#' @rdname wrappers
-#' @param x,y parameters
-#' @export
-add_ints <- function(x, y) {
-  .Call("wrap__add_ints", x, y)
-}
\ No newline at end of file
diff --git a/tests/extendrtests/man/wrappers.Rd b/tests/extendrtests/man/wrappers.Rd
index a2c74a366f..4b45ffc3ee 100644
--- a/tests/extendrtests/man/wrappers.Rd
+++ b/tests/extendrtests/man/wrappers.Rd
@@ -1,17 +1,11 @@
 % Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/wrappers.R
-\name{hello}
-\alias{hello}
-\alias{add_ints}
-\title{Wrappers for Rust functions.}
+\name{hello_world}
+\alias{hello_world}
+\title{Wrappers for Rust test functions.}
 \usage{
-hello()
-
-add_ints(x, y)
-}
-\arguments{
-\item{x, y}{parameters}
+hello_world()
 }
 \description{
-Wrappers for Rust functions.
+Wrappers for Rust test functions.
 }
diff --git a/tests/extendrtests/src/rust/Cargo.toml b/tests/extendrtests/src/rust/Cargo.toml
index 0ee70d704f..4afc483df7 100644
--- a/tests/extendrtests/src/rust/Cargo.toml
+++ b/tests/extendrtests/src/rust/Cargo.toml
@@ -16,7 +16,7 @@ crate-type = ["staticlib"]
 extendr-api = "*"
 
 [patch.crates-io]
-extendr-api = { git = "https://github.com/clauswilke/extendr", branch = "reg-forwarding" }
-extendr-engine = { git = "https://github.com/clauswilke/extendr", branch = "reg-forwarding" }
-extendr-macros = { git = "https://github.com/clauswilke/extendr", branch = "reg-forwarding" }
+extendr-api = { git = "https://github.com/extendr/extendr" }
+extendr-engine = { git = "https://github.com/extendr/extendr" }
+extendr-macros = { git = "https://github.com/extendr/extendr" }
 #libR-sys = { git = "https://github.com/extendr/libR-sys" }
diff --git a/tests/extendrtests/src/rust/src/lib.rs b/tests/extendrtests/src/rust/src/lib.rs
index b840db6c3e..be75ee6a3c 100644
--- a/tests/extendrtests/src/rust/src/lib.rs
+++ b/tests/extendrtests/src/rust/src/lib.rs
@@ -1,19 +1,28 @@
 use extendr_api::*;
 
 #[extendr]
-fn hello() -> &'static str {
-    "hello"
+fn hello_world() -> &'static str {
+    "Hello world!"
 }
 
+// functions to test input/output conversion
 #[extendr]
-fn add_ints(x:i32, y:i32) -> i32 {
-    x + y
-}
+fn double_scalar(x: f64) -> f64 { x }
+#[extendr]
+fn int_scalar(x: i32) -> i32 { x }
+#[extendr]
+fn bool_scalar(x: bool) -> bool { x }
+#[extendr]
+fn char_scalar(x: String) -> String { x }
 
 
 // Macro to generate exports
 extendr_module! {
     mod extendrtests;
-    fn hello;
-    fn add_ints;
+    fn hello_world;
+
+    fn double_scalar;
+    fn int_scalar;
+    fn bool_scalar;
+    fn char_scalar;
 }
diff --git a/tests/extendrtests/tests/testthat/test-type-conversion.R b/tests/extendrtests/tests/testthat/test-type-conversion.R
new file mode 100644
index 0000000000..e1287cde18
--- /dev/null
+++ b/tests/extendrtests/tests/testthat/test-type-conversion.R
@@ -0,0 +1,31 @@
+test_that("Conversion of R types to Rust types and vice versa works", {
+  expect_equal(.Call(wrap__double_scalar, .45), .45)
+  expect_equal(.Call(wrap__double_scalar, 15L), 15)
+  expect_error(.Call(wrap__double_scalar, TRUE), "unable to convert")
+  expect_error(.Call(wrap__double_scalar, "abcxyz"), "unable to convert")
+  expect_error(.Call(wrap__double_scalar, NA_real_), "Input must not be NA")
+  expect_error(.Call(wrap__double_scalar, c(.45, .46)), "Input must be of length 1")
+  
+  expect_equal(.Call(wrap__int_scalar, 15L), 15L)
+  expect_equal(.Call(wrap__int_scalar, 4.4), 4L) # is this deliberate? seems dangerous
+  expect_error(.Call(wrap__int_scalar, TRUE), "unable to convert")
+  expect_error(.Call(wrap__int_scalar, "abcxyz"), "unable to convert")
+  expect_error(.Call(wrap__int_scalar, NA_integer_), "Input must not be NA")
+  expect_error(.Call(wrap__int_scalar, 1L:5L), "Input must be of length 1")
+  
+  expect_equal(.Call(wrap__bool_scalar, TRUE), TRUE)
+  expect_equal(.Call(wrap__bool_scalar, FALSE), FALSE)
+  expect_error(.Call(wrap__bool_scalar, .45), "Not a logical object")
+  expect_error(.Call(wrap__bool_scalar, 15L), "Not a logical object")
+  expect_error(.Call(wrap__bool_scalar, "abcxyz"), "Not a logical object")
+  expect_error(.Call(wrap__bool_scalar, NA), "Input must not be NA")
+  expect_error(.Call(wrap__bool_scalar, c(TRUE, FALSE, TRUE)), "Input must be of length 1")
+  
+  expect_equal(.Call(wrap__char_scalar, "abcxyz"), "abcxyz")
+  expect_error(.Call(wrap__char_scalar, .45), "not a string object")
+  expect_error(.Call(wrap__char_scalar, 15L), "not a string object")
+  expect_error(.Call(wrap__char_scalar, TRUE), "not a string object")
+  expect_error(.Call(wrap__char_scalar, NA_character_), "Input must not be NA")
+  expect_error(.Call(wrap__char_scalar, c("hello", "world")), "not a string object") # why this error message and not "Input must be of length 1"?
+})
+
diff --git a/tests/extendrtests/tests/testthat/test-wrappers.R b/tests/extendrtests/tests/testthat/test-wrappers.R
index ccf4283815..3a37850dce 100644
--- a/tests/extendrtests/tests/testthat/test-wrappers.R
+++ b/tests/extendrtests/tests/testthat/test-wrappers.R
@@ -1,4 +1,3 @@
-test_that("Call to Rust functions work", {
-  expect_equal(hello(), "hello")
-  expect_equal(add_ints(3L, 5L), 8L)
+test_that("Call to Rust via wrapper functions works", {
+  expect_equal(hello_world(), "Hello world!")
 })