diff --git a/atst/app.py b/atst/app.py
index d73188cf..29476ed8 100644
--- a/atst/app.py
+++ b/atst/app.py
@@ -222,7 +222,7 @@ def make_config(direct_config=None):
         config.read_dict({"default": direct_config})
 
     # Assemble DATABASE_URI value
-    database_uri = "postgres://{}:{}@{}:{}/{}".format(  # pragma: allowlist secret
+    database_uri = "postgresql://{}:{}@{}:{}/{}".format(  # pragma: allowlist secret
         config.get("default", "PGUSER"),
         config.get("default", "PGPASSWORD"),
         config.get("default", "PGHOST"),