diff --git a/.github/workflows/python_package.yaml b/.github/workflows/python_package.yaml
index dd6f9b0..ed6a7b1 100644
--- a/.github/workflows/python_package.yaml
+++ b/.github/workflows/python_package.yaml
@@ -4,7 +4,7 @@ on: [push]
 
 jobs:
   pytest:
-    name: pytest for py${{ matrix.python-version }} on ${{ matrix.os }}
+    name: pytest for py${{ matrix.python-version }} on ${{ matrix.os }}${{ matrix.unpinned && ', unpinned' || '' }}
 
     runs-on: ${{ matrix.os }}
     strategy:
@@ -12,6 +12,14 @@ jobs:
       matrix:
         python-version: [3.9, '3.10', '3.11', '3.12']
         os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
+        unpinned: [false]
+        include:
+          # One job installs the package without the pins of
+          # requirements.txt, as pip install microstructpy does, so that the
+          # tests see the dependency versions that users get.
+          - python-version: '3.12'
+            os: 'ubuntu-latest'
+            unpinned: true
 
     steps:
     - uses: actions/checkout@main
@@ -33,6 +41,7 @@ jobs:
         pip install setuptools wheel
         pip install flake8 pytest pytest-cov coveralls
     - name: Install package requirements
+      if: ${{ !matrix.unpinned }}
       run: pip install -r requirements.txt
     - name: Install package
       run: pip install -e .
@@ -47,6 +56,7 @@ jobs:
       run: pytest --cov=src tests/
       
     - name: Coveralls
+      if: ${{ !matrix.unpinned }}
       env:
         COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
         COVERALLS_FLAG_NAME: py${{ matrix.python-version }} on ${{ matrix.os }}
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 9a6437b..aaa85a2 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -6,6 +6,24 @@ All notable changes to this project will be documented in this file.
 The format is based on `Keep a Changelog`_,
 and this project adheres to `Semantic Versioning`_.
 
+`1.6.1`_ - 2026-10-19
+--------------------------
+Fixed
+'''''
+- ``pip install microstructpy`` installs versions of numpy and MeshPy that
+  the package works with: numpy below 2 and MeshPy below 2026. With numpy 2,
+  the text files of the meshes cannot be read back, since numpy writes
+  integers as ``np.int64(4)``, and ``tangent_sphere`` fails. With MeshPy
+  2026, TetGen no longer keeps the elements of 3D meshes under
+  ``max_volume``. numpy below 2 has no wheels for Python 3.13 and later, so
+  pip builds it from source there, which needs a compiler.
+
+Changed
+'''''''
+- The continuous integration also runs the tests on an installation without
+  the pins of ``requirements.txt``, as ``pip install microstructpy`` does, so
+  that it sees the dependency versions that users get.
+
 `1.6.0`_ - 2026-10-18
 --------------------------
 Added
@@ -508,7 +526,8 @@ Added
 
 .. LINKS
 
-.. _`Unreleased`: https://github.com/kip-hart/MicroStructPy/compare/v1.6.0...HEAD
+.. _`Unreleased`: https://github.com/kip-hart/MicroStructPy/compare/v1.6.1...HEAD
+.. _`1.6.1`: https://github.com/kip-hart/MicroStructPy/compare/v1.6.0...v1.6.1
 .. _`1.6.0`: https://github.com/kip-hart/MicroStructPy/compare/v1.5.9...v1.6.0
 .. _`1.5.9`: https://github.com/kip-hart/MicroStructPy/compare/v1.5.8...v1.5.9
 .. _`1.5.8`: https://github.com/kip-hart/MicroStructPy/compare/v1.5.7...v1.5.8
diff --git a/docs/source/sphinx_gallery/plot_demos.py b/docs/source/sphinx_gallery/plot_demos.py
index b34a9b5..cb78bbc 100644
--- a/docs/source/sphinx_gallery/plot_demos.py
+++ b/docs/source/sphinx_gallery/plot_demos.py
@@ -24,7 +24,7 @@
 # them is edited, and the build would serve stale figures.
 #
 # Managed by docs/example_digest.py. Do not edit by hand.
-EXAMPLES_DIGEST = 'e16a7babf54a2cfe'
+EXAMPLES_DIGEST = '1cc876c00916b073'
 
 example_dir = '../../../src/microstructpy/examples'
 
diff --git a/setup.py b/setup.py
index 12e16d2..672805f 100644
--- a/setup.py
+++ b/setup.py
@@ -81,8 +81,8 @@ def find_version(*fname):
         'pybind11',  # must come before meshpy for successful install
         'lsq-ellipse',
         'matplotlib>=3.4.0',
-        'meshpy>=2018.2.1',
-        'numpy>=1.22.2',
+        'meshpy>=2018.2.1,<2026',  # TetGen of 2026 exceeds max_volume
+        'numpy>=1.22.2,<2',  # numpy 2 breaks the mesh text files
         'pygmsh>=7.0.2',
         'pyquaternion',
         'pyvoro-rimoli>=1.4.0',  # pyvoro with the current Voro++
diff --git a/src/microstructpy/__init__.py b/src/microstructpy/__init__.py
index a42448a..f383ffd 100644
--- a/src/microstructpy/__init__.py
+++ b/src/microstructpy/__init__.py
@@ -4,4 +4,4 @@
 import microstructpy.seeding
 import microstructpy.verification
 
-__version__ = '1.6.0'
+__version__ = '1.6.1'