diff --git a/.circleci/config.yml b/.circleci/config.yml
index 5243653..ee1a9e5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -3,7 +3,7 @@ version: 2.0
 jobs:
   deploy_to_playground:
     docker:
-      - image: circleci/python:3.6-stretch
+      - image: circleci/python:3.12-stretch
     steps:
       - checkout
       - run:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 96bf2de..0aef203 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,26 +13,30 @@ jobs:
     name: ${{ matrix.name }}
     runs-on: ${{ matrix.os }}
     strategy:
+      fail-fast: false
       matrix:
         include:
-          - name: Linux py36
-            os: ubuntu-16.04
-            pyversion: '3.6'
-          - name: Linux py37
-            os: ubuntu-latest
-            pyversion: '3.7'
           - name: Linux py38
             os: ubuntu-latest
             pyversion: '3.8'
           - name: Linux py39
             os: ubuntu-latest
             pyversion: '3.9'
-          - name: MacOS py38
+          - name: Linux py310
+            os: ubuntu-latest
+            pyversion: '3.10'
+          - name: Linux py311
+            os: ubuntu-latest
+            pyversion: '3.11'
+          - name: Linux py312
+            os: ubuntu-latest
+            pyversion: '3.12'
+          - name: MacOS py312
             os: macos-latest
-            pyversion: '3.8'
-          - name: Windows py38
+            pyversion: '3.12'
+          - name: Windows py312
             os: windows-latest
-            pyversion: '3.8'
+            pyversion: '3.12'
 
     steps:
       - uses: actions/checkout@v2
diff --git a/dash_slicer/__init__.py b/dash_slicer/__init__.py
index 6d19f01..1f34e0b 100644
--- a/dash_slicer/__init__.py
+++ b/dash_slicer/__init__.py
@@ -5,5 +5,5 @@
 from .slicer import VolumeSlicer  # noqa: F401
 
 
-__version__ = "0.3.0"
+__version__ = "0.3.1"
 version_info = tuple(map(int, __version__.split(".")))
diff --git a/dash_slicer/utils.py b/dash_slicer/utils.py
index 64e0516..81db7cb 100644
--- a/dash_slicer/utils.py
+++ b/dash_slicer/utils.py
@@ -81,7 +81,7 @@ def mask_to_coloured_slices(mask, axis, color=None):
     # Check the mask
     if not isinstance(mask, np.ndarray):
         raise TypeError("Mask must be an ndarray or None.")
-    elif mask.dtype not in (np.bool, np.uint8):
+    elif mask.dtype not in (bool, np.uint8):
         raise ValueError(f"Mask must have bool or uint8 dtype, not {mask.dtype}.")
 
     mask = mask.astype(np.uint8, copy=False)  # need int to index