diff --git a/.evergreen/run-tests.sh b/.evergreen/run-tests.sh
index d647955059..fbe310ad1e 100755
--- a/.evergreen/run-tests.sh
+++ b/.evergreen/run-tests.sh
@@ -37,7 +37,7 @@ export PIP_QUIET=1  # Quiet by default
 export PIP_PREFER_BINARY=1 # Prefer binary dists by default
 
 set +x
-PYTHON_IMPL=$(uv run python -c "import platform; print(platform.python_implementation())")
+PYTHON_IMPL=$(uv run --frozen python -c "import platform; print(platform.python_implementation())")
 
 # Try to source local Drivers Secrets
 if [ -f ./secrets-export.sh ]; then
@@ -49,11 +49,11 @@ fi
 
 # Start compiling the args we'll pass to uv.
 # Run in an isolated environment so as not to pollute the base venv.
-UV_ARGS=("--isolated --extra test")
+UV_ARGS=("--isolated --frozen --extra test")
 
 # Ensure C extensions if applicable.
 if [ -z "${NO_EXT:-}" ] && [ "$PYTHON_IMPL" = "CPython" ]; then
-    uv run tools/fail_if_no_c.py
+    uv run --frozen tools/fail_if_no_c.py
 fi
 
 if [ "$AUTH" != "noauth" ]; then
@@ -239,7 +239,7 @@ if [ -n "$PERF_TEST" ]; then
 fi
 
 echo "Running $AUTH tests over $SSL with python $(uv python find)"
-uv run python -c 'import sys; print(sys.version)'
+uv run --frozen python -c 'import sys; print(sys.version)'
 
 
 # Run the tests, and store the results in Evergreen compatible XUnit XML
diff --git a/.evergreen/scripts/setup-dev-env.sh b/.evergreen/scripts/setup-dev-env.sh
index 3f8d0c4292..ae4b44c626 100755
--- a/.evergreen/scripts/setup-dev-env.sh
+++ b/.evergreen/scripts/setup-dev-env.sh
@@ -32,11 +32,11 @@ if [ ! -d $BIN_DIR ]; then
   echo "export UV_PYTHON=$UV_PYTHON" >> $HERE/env.sh
 fi
 echo "Using python $UV_PYTHON"
-uv sync
-uv run --with pip pip install -e .
+uv sync --frozen
+uv run --frozen --with pip pip install -e .
 echo "Setting up python environment... done."
 
 # Ensure there is a pre-commit hook if there is a git checkout.
 if [ -d .git ] && [ ! -f .git/hooks/pre-commit ]; then
-    uv run pre-commit install
+    uv run --frozen pre-commit install
 fi
diff --git a/justfile b/justfile
index 6bcfe0c79c..8a076038a4 100644
--- a/justfile
+++ b/justfile
@@ -4,7 +4,7 @@ set dotenv-load
 set dotenv-filename := "./.evergreen/scripts/env.sh"
 
 # Commonly used command segments.
-uv_run := "uv run --isolated "
+uv_run := "uv run --isolated --frozen "
 typing_run := uv_run + "--group typing --extra aws --extra encryption --extra ocsp --extra snappy --extra test --extra zstd"
 docs_run := uv_run + "--extra docs"
 doc_build := "./doc/_build"