diff --git a/dissect/archive/c_wim.py b/dissect/archive/c_wim.py
index c23aa7a..074afe8 100644
--- a/dissect/archive/c_wim.py
+++ b/dissect/archive/c_wim.py
@@ -232,8 +232,7 @@
 } WIMHASH;
 """
 
-c_wim = cstruct()
-c_wim.load(wim_def)
+c_wim = cstruct().load(wim_def)
 
 WIM_IMAGE_TAG = b"MSWIM\x00\x00\x00"
 HEADER_FLAG = c_wim.HEADER_FLAG
diff --git a/pyproject.toml b/pyproject.toml
index 50ad469..cff15b8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,8 +25,8 @@ classifiers = [
   "Topic :: Utilities",
 ]
 dependencies = [
-    "dissect.cstruct>=3.0.dev,<4.0.dev",
-    "dissect.util>=3.0.dev,<4.0.dev",
+    "dissect.cstruct>3,<5",
+    "dissect.util>2,<4",
 ]
 dynamic = ["version"]
 
diff --git a/tox.ini b/tox.ini
index 1fa283f..5bea6cd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,11 +11,17 @@ minversion = 4.4.3
 requires = virtualenv>=20.16.6
 
 [testenv]
-extras = full
 deps =
     pytest
     pytest-cov
     coverage
+# Unfortunately, tox does not allow separate installation flags for the project
+# dependencies and the test dependencies. When running tox, we want to install the
+# project dependencies with the --pre flag, so that we get the latest version of all
+# dependencies. We do the installation step ourselves for this reason.
+skip_install = true
+commands_pre =
+    pip install --pre -e .[full]
 commands =
     pytest --basetemp="{envtmpdir}" {posargs:--color=yes --cov=dissect --cov-report=term-missing -v tests}
     coverage report