diff --git a/.github/workflows/test_and_deploy.yml b/.github/workflows/test_and_deploy.yml
index 0015282..dc9abf7 100644
--- a/.github/workflows/test_and_deploy.yml
+++ b/.github/workflows/test_and_deploy.yml
@@ -55,7 +55,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        - os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:
       - name: Checkout repository
diff --git a/src/brainreg/backend/niftyreg/niftyreg_binaries.py b/src/brainreg/backend/niftyreg/niftyreg_binaries.py
index 0230c6e..0f9b4a0 100644
--- a/src/brainreg/backend/niftyreg/niftyreg_binaries.py
+++ b/src/brainreg/backend/niftyreg/niftyreg_binaries.py
@@ -67,8 +67,8 @@ def get_binary(program_name: str) -> Path:
         bin_path = packaged_binaries_folder / os_folder_name / program_name
 
     # Append exe label to Windows executables
-    # It looks like subprocess is actually able to cope without the .exe appended,
-    # but just to be safe we'll include it on Windows OS calls
+    # It looks like subprocess is actually able to cope without the .exe
+    # appended, but just to be safe we'll include it on Windows OS calls
     if _IS_WINDOWS_OS:
         bin_path = bin_path.parent / f"{bin_path.stem}.exe"
     return bin_path
diff --git a/tests/tests/test_backend/test_niftyreg_detection.py b/tests/tests/test_backend/test_niftyreg_detection.py
index 79c4190..d8b54b1 100644
--- a/tests/tests/test_backend/test_niftyreg_detection.py
+++ b/tests/tests/test_backend/test_niftyreg_detection.py
@@ -13,11 +13,12 @@ def packaged_binaries_are_used() -> Tuple[bool, Path]:
     """
     Return a (bool, Path) tuple which has the values:
         boolean:
-            TRUE if the get_binary function points to one of the niftyreg binaries
-             that are included with the package.
+            TRUE if the get_binary function points to one of the niftyreg
+            binaries that are included with the package.
             FALSE otherwise.
         Path:
-            The path to the folder containing the niftyreg binaries that were found
+            The path to the folder containing the niftyreg binaries that
+            were found.
     """
     using_binary = get_binary("reg_aladin")
     return (
@@ -29,21 +30,34 @@ def packaged_binaries_are_used() -> Tuple[bool, Path]:
 def test_conda_with_niftyreg():
     """
     Check the following:
-    - If we are not in a conda environment, the packaged niftyreg binaries are used by the backend
-    - If we are in a conda environment and niftyreg is not conda-installed, the packaged niftyreg binaries are used by the backend
-    - If we are in a conda environment and niftyreg IS conda-installed, the conda-installed binaries are used by the backend.
+    - If we are not in a conda environment, the packaged niftyreg binaries
+    are used by the backend
+    - If we are in a conda environment and niftyreg is not conda-installed,
+    the packaged niftyreg binaries are used by the backend
+    - If we are in a conda environment and niftyreg IS conda-installed,
+    the conda-installed binaries are used by the backend.
+
+    We need the assert_msg's to get round mypy thinking we're passing tuples
+    to assert (since Tuples always evaluate to true, and mypy wants to split
+    long code lines).
     """
     if "CONDA_PREFIX" not in os.environ:
         # We are not in a conda envrionment
         # _CONDA_NIFTYREG_BINARY_PATH should be none
-        assert (
-            _CONDA_NIFTYREG_BINARY_PATH is None
-        ), f"Not in a conda environment but _CONDA_NIFTYREG_BINARY_PATH is non-None: {_CONDA_NIFTYREG_BINARY_PATH}"
+        assert_msg = (
+            "Not in a conda environment but "
+            "_CONDA_NIFTYREG_BINARY_PATH is non-None: "
+            f"{_CONDA_NIFTYREG_BINARY_PATH}"
+        )
+        assert _CONDA_NIFTYREG_BINARY_PATH is None, assert_msg
 
         using_packaged_binaries, bin_folder = packaged_binaries_are_used()
-        assert (
-            using_packaged_binaries
-        ), f"There is no CONDA_PREFIX, but non-packaged binaries in {bin_folder} are being used!"
+        assert_msg = (
+            "There is no CONDA_PREFIX, "
+            f"but non-packaged binaries in {bin_folder} "
+            "are being used!"
+        )
+        assert using_packaged_binaries, assert_msg
     else:
         # We are in a conda environment.
         # Either this environment does not have niftyreg installed, or it does.
@@ -51,9 +65,19 @@ def test_conda_with_niftyreg():
             # Apparently niftyreg is not installed in this environment
             # Assert the located binaries are the packaged ones
             using_packaged_binaries, bin_folder = packaged_binaries_are_used()
-            assert using_packaged_binaries, f"Conda environment without niftyreg installed exists, but non-packaged binaries in {bin_folder} are being used."
+            assert_msg = (
+                "Conda environment without niftyreg installed exists, "
+                f"but non-packaged binaries in {bin_folder} "
+                "are being used."
+            )
+            assert using_packaged_binaries, assert_msg
         else:
             # We are in a conda environment that _has_ niftyreg conda-installed
             # Assert that we are using the CONDA-installed binaries
             using_packaged_binaries, bin_folder = packaged_binaries_are_used()
-            assert not using_packaged_binaries, f"Packaged binaries are being used despite appearing to be installed by CONDA at {_CONDA_NIFTYREG_BINARY_PATH}"
+            assert_msg = (
+                "Packaged binaries are being used, "
+                "despite niftyreg appearing to be installed by CONDA "
+                f" at {_CONDA_NIFTYREG_BINARY_PATH}"
+            )
+            assert not using_packaged_binaries, assert_msg