diff --git a/.github/workflows/openconcept.yaml b/.github/workflows/openconcept.yaml
index ff1480e7..d0ae036b 100644
--- a/.github/workflows/openconcept.yaml
+++ b/.github/workflows/openconcept.yaml
@@ -27,7 +27,7 @@ jobs:
         PYTHON_VERSION_LATEST: ['3.11']
         PIP_VERSION_OLDEST: ['23.0.1']  # pip>=23.1 cannot build the oldest OpenMDAO
         SETUPTOOLS_VERSION_OLDEST: ['66.0.0']  # setuptools >= 67.0.0 can't build the oldest OpenMDAO
-        NUMPY_VERSION_OLDEST: ['1.20']  # latest is most recent on PyPI
+        NUMPY_VERSION_OLDEST: ['1.21']  # latest is most recent on PyPI
         SCIPY_VERSION_OLDEST: ['1.7.0']  # latest is most recent on PyPI
         OPENMDAO_VERSION_OLDEST: ['3.21']  # latest is most recent on PyPI
       fail-fast: false
diff --git a/doc/index.rst b/doc/index.rst
index f99a14ad..73cdf1e8 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -68,7 +68,7 @@ OpenConcept is tested regularly on builds with the oldest and latest supported p
      - 3.30
    * - NumPy
      - 1.20
-     - latest
+     - 1.26
    * - SciPy
      - 1.7.0
      - latest
diff --git a/readme.md b/readme.md
index e542ccde..b69333f7 100644
--- a/readme.md
+++ b/readme.md
@@ -55,7 +55,7 @@ OpenConcept is tested regularly on builds with the oldest and latest supported p
 | ------- | ------- | ------ |
 | Python | 3.8 | 3.11 |
 | OpenMDAO | 3.21 | 3.30 |
-| NumPy | 1.20 | latest |
+| NumPy | 1.20 | 1.26 |
 | SciPy | 1.7.0 | latest |
 | OpenAeroStruct | latest | latest |
 
diff --git a/setup.py b/setup.py
index 5957e56a..fd4c0282 100644
--- a/setup.py
+++ b/setup.py
@@ -40,7 +40,7 @@
     install_requires=[
         # Update the oldest package versions in the GitHub Actions build file, the readme,
         # and the index.rst file in the docs when you change these
-        "numpy>=1.20",
+        "numpy >=1.20, <=1.26",  # OpenMDAO is not compatible with NumPy v2
         "scipy>=1.7.0",
         "openmdao >=3.21, <=3.30",
     ],