diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a742812..afd2767 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -67,7 +67,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: ["ubuntu-24.04", "ubuntu-24.04-arm", "macos-13", "macos-14"]
+        os: ["ubuntu-24.04", "ubuntu-24.04-arm", "macos-14"]
 
     runs-on: ${{ matrix.os }}
 
diff --git a/.github/workflows/prerelease.yml b/.github/workflows/prerelease.yml
index 6fd7abf..6415e56 100644
--- a/.github/workflows/prerelease.yml
+++ b/.github/workflows/prerelease.yml
@@ -41,8 +41,6 @@ jobs:
             arch: auto
           - os: macos-14
             arch: auto
-          - os: macos-13
-            arch: auto
 
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
diff --git a/.github/workflows/stable-release-workflow.yml b/.github/workflows/stable-release-workflow.yml
index 1981e6c..f944bfd 100644
--- a/.github/workflows/stable-release-workflow.yml
+++ b/.github/workflows/stable-release-workflow.yml
@@ -40,8 +40,6 @@ jobs:
             arch: auto
           - os: macos-14
             arch: auto
-          - os: macos-13
-            arch: auto
 
     steps:
     - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
diff --git a/tunits/core/__init__.pyi b/tunits/core/__init__.pyi
index 1c6eca3..aa688fb 100644
--- a/tunits/core/__init__.pyi
+++ b/tunits/core/__init__.pyi
@@ -229,6 +229,8 @@ class Value(Generic[NumericalT], WithUnit, np.generic, SupportsIndex):
     real: 'Value'
     imag: 'Value'
 
+    # needed because np.generic declars __new__ as abstract.
+    def __new__(cls: type[T], *args: Any, **kwargs: Any) -> T: ...
     @classmethod
     def from_proto(cls: type[T], msg: tunits_pb2.Value) -> T: ...
     def to_proto(self, msg: tunits_pb2.Value | None = None) -> tunits_pb2.Value: ...