diff --git a/modules/postgresql.nix b/modules/postgresql.nix
index db07d43..f170c43 100644
--- a/modules/postgresql.nix
+++ b/modules/postgresql.nix
@@ -50,7 +50,7 @@ in
       };
 
       dbConfig = passwordCfgs: {
-        services.postgresql.enable = (builtins.length passwordCfgs) > 0;
+        services.postgresql.enable = lib.mkDefault ((builtins.length passwordCfgs) > 0);
         services.postgresql.ensureDatabases = map ({ database, ... }: database) passwordCfgs;
         services.postgresql.ensureUsers = map ({ username, database, ... }: {
           name = username;
diff --git a/test/modules/postgresql.nix b/test/modules/postgresql.nix
index 22e9860..522d70c 100644
--- a/test/modules/postgresql.nix
+++ b/test/modules/postgresql.nix
@@ -36,6 +36,20 @@ in
     expr = testConfig {};
   };
 
+  testPostgresManualOptions = {
+    expected = {
+      services.postgresql = {
+        enable = true;
+        ensureUsers = [];
+        ensureDatabases = [];
+      };
+      systemd.services.postgresql.postStart = "";
+    };
+    expr = testConfig {
+      services.postgresql.enable = true;
+    };
+  };
+
   testPostgresOneWithoutPassword = {
     expected = {
       services.postgresql = {