diff --git a/fzw/settings.py b/fzw/settings.py
index b5c3223..cb12c27 100644
--- a/fzw/settings.py
+++ b/fzw/settings.py
@@ -14,6 +14,8 @@
 
 import dj_database_url  # type: ignore
 
+from fzw.util.common import smart_bool, smart_bool_or_none
+
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
 BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 DATA_DIR = os.path.join(BASE_DIR, 'data')
@@ -26,7 +28,7 @@
 SECRET_KEY = os.environ.get('SECRET_KEY', 'abracadabra')
 
 # SECURITY WARNING: don't run with debug turned on in production!
-DEBUG = bool(int(os.environ.get('DEBUG', '0')))
+DEBUG = smart_bool(os.getenv("DEBUG"))
 
 BACKEND_HOST = os.environ.get('BACKEND_HOST', '*')
 DATABASE_URL = os.environ.get(
@@ -178,7 +180,11 @@
     },
 }
 
-if not DEBUG:
+HSTS_MODE_ENABLED = smart_bool_or_none(os.getenv("HSTS_MODE_ENABLED"))
+if HSTS_MODE_ENABLED is None:
+    HSTS_MODE_ENABLED = not DEBUG
+
+if HSTS_MODE_ENABLED:
     SECURE_HSTS_SECONDS = 60
     SECURE_HSTS_INCLUDE_SUBDOMAINS = True
     SECURE_SSL_REDIRECT = True
diff --git a/fzw/util/__init__.py b/fzw/util/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/fzw/util/common.py b/fzw/util/common.py
new file mode 100644
index 0000000..ec5f059
--- /dev/null
+++ b/fzw/util/common.py
@@ -0,0 +1,21 @@
+from typing import Any, Optional
+
+_TRUTHY_VALUES = {"t", "true", "1"}
+_FALSY_VALUES = {"f", "false", "0"}
+
+
+def smart_bool_or_none(value: Any) -> Optional[bool]:
+    if isinstance(value, str):
+        normalized_value = value.lower()
+        if normalized_value in _TRUTHY_VALUES:
+            return True
+        if normalized_value in _FALSY_VALUES:
+            return False
+        return None
+    if value is None:
+        return None
+    return bool(value)
+
+
+def smart_bool(value: Any) -> bool:
+    return smart_bool_or_none(value) or False
diff --git a/tests/util/__init__.py b/tests/util/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/util/test_common.py b/tests/util/test_common.py
new file mode 100644
index 0000000..0036a5f
--- /dev/null
+++ b/tests/util/test_common.py
@@ -0,0 +1,55 @@
+import pytest
+
+from fzw.util.common import smart_bool, smart_bool_or_none
+
+
+@pytest.mark.parametrize(
+    "input,output",
+    (
+        (False, False),
+        (True, True),
+        (0, False),
+        (1, True),
+        (1.0, True),
+        (0.1, True),
+        ("", False),
+        ("none", False),
+        ("nil", False),
+        ("0", False),
+        ("false", False),
+        ("False", False),
+        ("f", False),
+        ("1", True),
+        ("true", True),
+        ("True", True),
+        ("t", True),
+    ),
+)
+def test_smart_bool(input, output):
+    assert smart_bool(input) == output
+
+
+@pytest.mark.parametrize(
+    "input,output",
+    (
+        (False, False),
+        (True, True),
+        (0, False),
+        (1, True),
+        (1.0, True),
+        (0.1, True),
+        ("", None),
+        ("none", None),
+        ("nil", None),
+        ("0", False),
+        ("false", False),
+        ("False", False),
+        ("f", False),
+        ("1", True),
+        ("true", True),
+        ("True", True),
+        ("t", True),
+    ),
+)
+def test_smart_bool_or_none(input, output):
+    assert smart_bool_or_none(input) == output