diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 26bbd8b10..b2d3ea7cd 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -2,7 +2,7 @@ name: Build and test
 
 # This file tests the claimed support range of NiBabel including
 #
-# * Operating systems: Linux, Windows (x64 & x86), OSX
+# * Operating systems: Linux, Windows (x64 & x86), macOS
 # * Dependencies: minimum requirements, optional requirements
 # * Installation methods: setup.py, sdist, wheel, archive
 
@@ -112,7 +112,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: ['ubuntu-latest', 'windows-latest', 'macos-13', 'macos-latest']
+        os: ['ubuntu-latest', 'windows-latest', 'macos-14', 'macos-latest']
         python-version:
           - "3.9"
           - "3.10"
@@ -142,48 +142,56 @@ jobs:
             dependencies: 'min'
         exclude:
           # Use ubuntu-latest to cover the whole range of Python. For Windows
-          # and OSX, checking oldest and newest should be sufficient.
+          # and macOS, checking oldest and newest should be sufficient.
           - os: windows-latest
             python-version: "3.10"
           - os: windows-latest
             python-version: "3.11"
           - os: windows-latest
             python-version: "3.12"
-          - os: macos-13
+          - os: windows-latest
+            python-version: "3.13"
+          - os: windows-latest
+            python-version: "3.13t"
+          - os: macos-14
+            python-version: "3.9"
+          - os: macos-14
             python-version: "3.10"
-          - os: macos-13
-            python-version: "3.11"
-          - os: macos-13
-            python-version: "3.12"
+          - os: macos-14
+            python-version: "3.14"
+          - os: macos-14
+            python-version: "3.14t"
           - os: macos-latest
             python-version: "3.10"
           - os: macos-latest
             python-version: "3.11"
           - os: macos-latest
             python-version: "3.12"
+          - os: macos-latest
+            python-version: "3.13"
+          - os: macos-latest
+            python-version: "3.13t"
 
           ## Unavailable architectures
           # x86 is available for Windows
           - os: ubuntu-latest
             architecture: x86
-          - os: macos-latest
+          - os: macos-14
             architecture: x86
-          - os: macos-13
+          - os: macos-latest
             architecture: x86
           # arm64 is available for macos-14+
           - os: ubuntu-latest
             architecture: arm64
           - os: windows-latest
             architecture: arm64
-          - os: macos-13
-            architecture: arm64
-          # x64 is not available for macos-14+
+          # x64 is not available for macos-15
           - os: macos-latest
             architecture: x64
 
           ## Reduced support
-          # Drop pre tests for macos-13
-          - os: macos-13
+          # Drop pre tests for macos-14
+          - os: macos-14
             dependencies: pre
           # Drop pre tests for SPEC-0-unsupported Python versions
           - python-version: '3.9'
diff --git a/doc/source/installation.rst b/doc/source/installation.rst
index 983968c50..f6c1c0099 100644
--- a/doc/source/installation.rst
+++ b/doc/source/installation.rst
@@ -36,7 +36,7 @@ If you are not using a Linux package manager, then best way to install NiBabel
 is via pip_.  If you don't have pip already, follow the `pip install
 instructions`_.
 
-Then open a terminal (``Terminal.app`` on OSX, ``cmd`` or ``Powershell`` on
+Then open a terminal (``Terminal.app`` on macOS, ``cmd`` or ``Powershell`` on
 Windows), and type::
 
     pip install nibabel
diff --git a/nibabel/tests/test_floating.py b/nibabel/tests/test_floating.py
index 82c8e667a..34498ab38 100644
--- a/nibabel/tests/test_floating.py
+++ b/nibabel/tests/test_floating.py
@@ -117,7 +117,7 @@ def test_check_nmant_nexp():
         ti = type_info(t)
         if ti['nmant'] not in (105, 106):  # This check does not work for PPC double pair
             assert _check_nmant(t, ti['nmant'])
-        # Test fails for longdouble after blacklisting of OSX powl as of numpy
+        # Test fails for longdouble after blacklisting of macOS powl as of numpy
         # 1.12 - see https://github.com/numpy/numpy/issues/8307
         if t != np.longdouble or sys.platform != 'darwin':
             assert _check_maxexp(t, ti['maxexp'])
diff --git a/nibabel/tests/test_volumeutils.py b/nibabel/tests/test_volumeutils.py
index 1bd44cbd0..c7b2b3e81 100644
--- a/nibabel/tests/test_volumeutils.py
+++ b/nibabel/tests/test_volumeutils.py
@@ -1013,7 +1013,7 @@ def test_fname_ext_ul_case():
     with InTemporaryDirectory():
         with open('afile.TXT', 'w') as fobj:
             fobj.write('Interesting information')
-        # OSX usually has case-insensitive file systems; Windows also
+        # macOS usually has case-insensitive file systems; Windows also
         os_cares_case = not exists('afile.txt')
         with open('bfile.txt', 'w') as fobj:
             fobj.write('More interesting information')