diff --git a/tested/languages/haskell/generators.py b/tested/languages/haskell/generators.py
index c2897db7..7d5a0c9c 100644
--- a/tested/languages/haskell/generators.py
+++ b/tested/languages/haskell/generators.py
@@ -241,7 +241,7 @@ def convert_execution_unit(pu: PreparedExecutionUnit) -> str:
             if tc.testcase.is_main_testcase():
                 assert isinstance(tc.input, MainInput)
                 wrapped = [json.dumps(a) for a in tc.input.arguments]
-                result += indent + f"let mainArgs = [{' '.join(wrapped)}]\n"
+                result += indent + f"let mainArgs = [{' ,'.join(wrapped)}]\n"
                 result += (
                     indent
                     + f"result <- try (withArgs mainArgs {pu.submission_name}.main) :: IO (Either SomeException ())\n"
diff --git a/tests/exercises/dedup/evaluation/plan.yaml b/tests/exercises/dedup/evaluation/plan.yaml
new file mode 100644
index 00000000..9eef4f07
--- /dev/null
+++ b/tests/exercises/dedup/evaluation/plan.yaml
@@ -0,0 +1,9 @@
+- tab: "command_line_arguments"
+  testcases:
+  - arguments: [haskell, rust, java, haskell, c, rust]
+    stdout: "c haskell java rust"
+  - arguments: ["banana", "apple", "apple", "orange", "apple", "apple", "banana", "orange"]
+    stdout: "apple banana orange"
+  - arguments: []
+    stdout: "\n"
+  
\ No newline at end of file
diff --git a/tests/exercises/dedup/solution/solution.hs b/tests/exercises/dedup/solution/solution.hs
new file mode 100644
index 00000000..c5df5fbb
--- /dev/null
+++ b/tests/exercises/dedup/solution/solution.hs
@@ -0,0 +1,8 @@
+import Data.List (nub, sort)
+import System.Environment (getArgs)
+
+main :: IO ()
+main = do
+  args <- getArgs
+  let uniqueSorted = nub (sort args)
+  putStrLn (unwords uniqueSorted)
diff --git a/tests/test_cli_args.py b/tests/test_cli_args.py
new file mode 100644
index 00000000..debd85b3
--- /dev/null
+++ b/tests/test_cli_args.py
@@ -0,0 +1,30 @@
+import json
+from pathlib import Path
+
+import pytest
+import yaml
+
+from tested.datatypes import (
+    AdvancedNothingTypes,
+    AdvancedSequenceTypes,
+    BasicNumericTypes,
+)
+from tested.serialisation import NothingType, NumberType, SequenceType
+from tested.utils import sorted_no_duplicates, sorting_value_extract
+from tests.manual_utils import assert_valid_output, configuration, execute_config
+
+
+@pytest.mark.parametrize("language", ["haskell"])
+def test_cli_params(language: str, tmp_path: Path, pytestconfig: pytest.Config):
+    conf = configuration(
+        pytestconfig,
+        "dedup",
+        language,
+        tmp_path,
+        "plan.yaml",
+        "solution",
+    )
+    result = execute_config(conf)
+    print(result)
+    updates = assert_valid_output(result, pytestconfig)
+    assert updates.find_status_enum() == ["correct", "correct", "correct"]