diff --git a/README.md b/README.md
index 36dc912..01131c7 100644
--- a/README.md
+++ b/README.md
@@ -39,6 +39,7 @@ The app is served below `/fatima` by default. Configure the external path in
 flask:
   url_prefix: "/fatima"
   log_file: "/tmp/fatima.log"
+  database: "instance/calendar.sqlite"
 ```
 
 Set `URL_PREFIX` in the environment to override this value at deployment time.
@@ -83,6 +84,11 @@ For deployments, `APP_CONFIG` can point to a YAML file elsewhere. `SECRET_KEY`,
 override the corresponding values. `DATABASE` should be an absolute path to the
 SQLite file used in production.
 
+The YAML `flask.database` path is resolved relative to the directory containing
+the selected config file. If it is omitted, the app uses
+`instance/calendar.sqlite` beside `flask_fatima.py`; it no longer relies on
+Flask's environment-dependent inferred instance directory.
+
 At startup, the app prints a database summary to the Waitress log containing the
 resolved path, amount and status totals, distinct recorded-date total, and date
 range. Compare that path and those totals with the importer's output to confirm
diff --git a/config.example.yaml b/config.example.yaml
index 0089807..38c80c2 100644
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -5,6 +5,8 @@ flask:
   url_prefix: "/fatima"
   # Startup database summary log.
   log_file: "/tmp/fatima.log"
+  # Relative paths are resolved from the directory containing this config file.
+  database: "instance/calendar.sqlite"
 
 auth:
   username: "your-username"
diff --git a/flask_fatima.py b/flask_fatima.py
index 5369891..31d6215 100644
--- a/flask_fatima.py
+++ b/flask_fatima.py
@@ -39,7 +39,7 @@ class UrlPrefixMiddleware:
 
 
 def load_yaml_config(path):
-    config_path = Path(path)
+    config_path = Path(path).expanduser().resolve()
     if not config_path.is_file():
         raise RuntimeError(
             f"Configuration file not found: {config_path}. "
@@ -59,6 +59,14 @@ def load_yaml_config(path):
         "URL_PREFIX": normalize_url_prefix(flask_config.get("url_prefix", "/fatima")),
         "LOG_FILE": flask_config.get("log_file", "/tmp/fatima.log"),
     }
+    configured_database = flask_config.get("database")
+    if configured_database is not None:
+        if not isinstance(configured_database, str) or not configured_database.strip():
+            raise RuntimeError(f"{config_path}: flask.database must be a non-empty path")
+        database_path = Path(configured_database).expanduser()
+        if not database_path.is_absolute():
+            database_path = config_path.parent / database_path
+        required["DATABASE"] = str(database_path.resolve())
     missing = [
         name for name, value in required.items()
         if name != "URL_PREFIX" and (not isinstance(value, str) or not value)
@@ -119,7 +127,10 @@ def create_app(test_config=None):
     app = Flask(__name__)
     config_path = os.environ.get("APP_CONFIG", Path(app.root_path) / "config.yaml")
     app.config.from_mapping(load_yaml_config(config_path))
-    app.config.setdefault("DATABASE", str(Path(app.instance_path) / "calendar.sqlite"))
+    app.config.setdefault(
+        "DATABASE",
+        str(Path(__file__).resolve().parent / "instance" / "calendar.sqlite"),
+    )
 
     # Environment variables remain useful when deploying without a local file.
     for name in ("SECRET_KEY", "APP_USERNAME", "APP_PASSWORD", "DATABASE", "LOG_FILE"):
diff --git a/tests/test_app.py b/tests/test_app.py
index 3f89bad..1240b58 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -1,7 +1,7 @@
 import tempfile
 from pathlib import Path
 
-from flask_fatima import create_app, log_database_summary
+from flask_fatima import create_app, load_yaml_config, log_database_summary
 
 URL_PREFIX = "/fatima"
 
@@ -44,6 +44,27 @@ def test_database_summary_is_appended_to_log(capsys):
         assert "Fatima database:" in capsys.readouterr().out
 
 
+def test_database_path_is_resolved_relative_to_config_file():
+    with tempfile.TemporaryDirectory() as directory:
+        config_path = Path(directory) / "production.yaml"
+        config_path.write_text(
+            """
+flask:
+  secret_key: test-secret
+  database: data/calendar.sqlite
+auth:
+  username: user
+  password: pass
+""",
+            encoding="utf-8",
+        )
+
+        config = load_yaml_config(config_path)
+        assert config["DATABASE"] == str(
+            (Path(directory) / "data" / "calendar.sqlite").resolve()
+        )
+
+
 def test_prefix_applies_to_generated_links_and_unprefixed_routes_are_rejected():
     test_client = client()
     test_client.post(url("/login"), data={"username": "user", "password": "pass"})