diff --git a/.github/workflows/tests-dbt-version.yml b/.github/workflows/tests-dbt-version.yml
index 5abfbcc..e839842 100644
--- a/.github/workflows/tests-dbt-version.yml
+++ b/.github/workflows/tests-dbt-version.yml
@@ -26,7 +26,7 @@ jobs:
           pip install -q coverage pylint
           pip install -q dbt-core==${{ inputs.dbt-version }}.* dbt-duckdb==${{ inputs.dbt-version }}.* --force-reinstall --upgrade
           # FIX for protobuf issue: https://github.com/dbt-labs/dbt-core/issues/9759
-          pip install -q "apache-airflow<3.0.0" "protobuf>=4.25.3,<5.0.0" "opentelemetry-proto<1.28.0" --prefer-binary
+          pip install -q "apache-airflow<3.0.0" "opentelemetry-proto<1.28.0" --prefer-binary
           pip install -q .[test] --prefer-binary
           pip install -q dbt-core==${{ inputs.dbt-version }}.* dbt-duckdb==${{ inputs.dbt-version }}.* --force-reinstall --upgrade
           python --version
diff --git a/opendbt/__main__.py b/opendbt/__main__.py
index fec1134..13ecb70 100644
--- a/opendbt/__main__.py
+++ b/opendbt/__main__.py
@@ -1,19 +1,39 @@
 import argparse
+import os
 from pathlib import Path
 
 from opendbt import OpenDbtCli, default_project_dir, default_profiles_dir
 
 
+class EnvDefault(argparse.Action):
+    def __init__(
+        self, option_strings, dest, envvar, required=True, default=None, **kwargs
+    ):
+        default = os.environ.get(envvar, default)
+        if required and default:
+            required = False
+        super().__init__(
+            option_strings, dest, default=default, required=required, **kwargs
+        )
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        setattr(namespace, self.dest, values)
+
+
 def main():
     parser = argparse.ArgumentParser(description="OpenDBT CLI")
     parser.add_argument(
         "--project-dir",
         default=None,
+        action=EnvDefault,
+        envvar="DBT_PROJECT_DIR",
         help="Path to the dbt project directory. Defaults to the DBT_PROJECT_DIR environment variable or the current working directory.",
     )
     parser.add_argument(
         "--profiles-dir",
         default=None,
+        action=EnvDefault,
+        envvar="DBT_PROFILES_DIR",
         help="Path to the dbt profiles directory. Defaults to the DBT_PROFILES_DIR environment variable.",
     )
     ns, args = parser.parse_known_args()