diff --git a/NEWS.md b/NEWS.md
index c24dc96..5fc9b14 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -2,6 +2,8 @@
 
 ## Breaking changes
 
+* `env_exists()` now error if no argument is supplied.
+
 ## New features
 
 ## Minor improvements and fixes
diff --git a/R/env_exists.R b/R/env_exists.R
index 02dd1c9..bcef65d 100644
--- a/R/env_exists.R
+++ b/R/env_exists.R
@@ -1,4 +1,4 @@
-#' Check If Environment Names Already exists
+#' Check If Environment Already exists
 #'
 #' @inheritParams create_env
 #' @return Boolean.
@@ -7,14 +7,15 @@
 #' # Create the environment
 #' condathis::create_env(
 #'   packages = "fastqc",
-#'   env_name = "fastqc_env"
+#'   env_name = "fastqc-env"
 #' )
 #' # Check if exists
-#' condathis::env_exists("fastqc_env")
+#' condathis::env_exists("fastqc-env")
 #' #> [1] TRUE
 #' }
 #' @export
-env_exists <- function(env_name = "condathis-env") {
+env_exists <- function(env_name) {
+  rlang::check_required(env_name)
   available_envs <- list_envs()
   condathis_env_path <- env_name
   if (isTRUE(condathis_env_path %in% available_envs)) {
diff --git a/man/env_exists.Rd b/man/env_exists.Rd
index a7a6bb5..d0ec5f2 100644
--- a/man/env_exists.Rd
+++ b/man/env_exists.Rd
@@ -2,9 +2,9 @@
 % Please edit documentation in R/env_exists.R
 \name{env_exists}
 \alias{env_exists}
-\title{Check If Environment Names Already exists}
+\title{Check If Environment Already exists}
 \usage{
-env_exists(env_name = "condathis-env")
+env_exists(env_name)
 }
 \arguments{
 \item{env_name}{Character. Name of the Conda environment where the packages
@@ -14,17 +14,17 @@ are going to be installed. Defaults to 'condathis-env'.}
 Boolean.
 }
 \description{
-Check If Environment Names Already exists
+Check If Environment Already exists
 }
 \examples{
 \dontrun{
 # Create the environment
 condathis::create_env(
   packages = "fastqc",
-  env_name = "fastqc_env"
+  env_name = "fastqc-env"
 )
 # Check if exists
-condathis::env_exists("fastqc_env")
+condathis::env_exists("fastqc-env")
 #> [1] TRUE
 }
 }
diff --git a/tests/testthat/test-env_exists.R b/tests/testthat/test-env_exists.R
new file mode 100644
index 0000000..dd7b519
--- /dev/null
+++ b/tests/testthat/test-env_exists.R
@@ -0,0 +1,5 @@
+test_that("env_exists missing env_name", {
+  expect_error(env_exists())
+  expect_equal(env_exists(NULL), FALSE)
+  expect_equal(env_exists(NA), FALSE)
+})
diff --git a/tests/testthat/test-list_packages.R b/tests/testthat/test-list_packages.R
new file mode 100644
index 0000000..7335ae0
--- /dev/null
+++ b/tests/testthat/test-list_packages.R
@@ -0,0 +1,8 @@
+test_that("list packages on absent environment", {
+  testthat::expect_error(
+    object = {
+      list_packages(env_name = "non-existing-env")
+    },
+    class = "condathis_list_packages_missing_env"
+  )
+})