diff --git a/.github/workflows/pre-release.yml b/.github/workflows/pre-release.yml
index 630f09d99..4431c7135 100644
--- a/.github/workflows/pre-release.yml
+++ b/.github/workflows/pre-release.yml
@@ -33,7 +33,7 @@ jobs:
     strategy:
       matrix:
         os: ['ubuntu-latest', 'windows-latest', 'macos-latest']
-        python-version: ["3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
         architecture: ['x64', 'x86']
         install: ['pip']
         check: ['test']
@@ -54,6 +54,8 @@ jobs:
             architecture: x86
           - os: macos-latest
             architecture: x86
+          - python-version: '3.12'
+            architecture: x86
 
     env:
       DEPENDS: ${{ matrix.depends }}
@@ -72,6 +74,7 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
           architecture: ${{ matrix.architecture }}
+          allow-prereleases: true
       - name: Display Python version
         run: python -c "import sys; print(sys.version)"
       - name: Create virtual environment
diff --git a/nibabel/openers.py b/nibabel/openers.py
index 90c7774d1..9a024680a 100644
--- a/nibabel/openers.py
+++ b/nibabel/openers.py
@@ -78,6 +78,12 @@ def __init__(
             mtime=mtime,
         )
 
+    def seek(self, pos: int, whence: int = 0, /) -> int:
+        # Work around bug (gh-180111) in Python 3.12rc1, where seeking without
+        # flushing can cause write of excess null bytes
+        self.flush()
+        return super().seek(pos, whence)
+
 
 def _gzip_open(
     filename: str,
diff --git a/nibabel/tests/test_image_api.py b/nibabel/tests/test_image_api.py
index 091bc57e8..890619bad 100644
--- a/nibabel/tests/test_image_api.py
+++ b/nibabel/tests/test_image_api.py
@@ -25,6 +25,7 @@
 
 import io
 import pathlib
+import sys
 import warnings
 from functools import partial
 from itertools import product
@@ -579,6 +580,10 @@ def validate_from_url(self, imaker, params):
         del img
         del rt_img
 
+    @pytest.mark.xfail(
+        sys.version_info >= (3, 12),
+        reason='Response type for file: urls is not a stream in Python 3.12',
+    )
     def validate_from_file_url(self, imaker, params):
         tmp_path = self.tmp_path
 
diff --git a/tools/ci/env.sh b/tools/ci/env.sh
index dd2944312..3d37ad955 100644
--- a/tools/ci/env.sh
+++ b/tools/ci/env.sh
@@ -12,6 +12,6 @@ PYDICOM_MASTER="git+https://github.com/pydicom/pydicom.git@master"
 MIN_OPT_DEPENDS="matplotlib==1.5.3 pydicom==1.0.1 pillow==2.6"
 
 # Numpy and scipy upload nightly/weekly/intermittent wheels
-NIGHTLY_WHEELS="https://pypi.anaconda.org/scipy-wheels-nightly/simple"
+NIGHTLY_WHEELS="https://pypi.anaconda.org/scientific-python-nightly-wheels/simple"
 STAGING_WHEELS="https://pypi.anaconda.org/multibuild-wheels-staging/simple"
 PRE_PIP_FLAGS="--pre --extra-index-url $NIGHTLY_WHEELS --extra-index-url $STAGING_WHEELS"
diff --git a/tools/ci/install_dependencies.sh b/tools/ci/install_dependencies.sh
index f26c5204c..2ea4a524e 100755
--- a/tools/ci/install_dependencies.sh
+++ b/tools/ci/install_dependencies.sh
@@ -19,10 +19,10 @@ if [ -n "$EXTRA_PIP_FLAGS" ]; then
 fi
 
 if [ -n "$DEPENDS" ]; then
-    pip install ${EXTRA_PIP_FLAGS} --prefer-binary ${!DEPENDS}
+    pip install ${EXTRA_PIP_FLAGS} --only-binary :all: ${!DEPENDS}
     if [ -n "$OPTIONAL_DEPENDS" ]; then
         for DEP in ${!OPTIONAL_DEPENDS}; do
-            pip install ${EXTRA_PIP_FLAGS} --prefer-binary $DEP || true
+            pip install ${EXTRA_PIP_FLAGS} --only-binary :all: $DEP || true
 	done
     fi
 fi