diff --git a/modules/programs/aerc-accounts.nix b/modules/programs/aerc-accounts.nix
index 04f0165a0..8ebfef0bb 100644
--- a/modules/programs/aerc-accounts.nix
+++ b/modules/programs/aerc-accounts.nix
@@ -134,8 +134,9 @@ in {
 
       oauthParams = { auth, params }:
         if useOauth auth && params != null && params != { } then
-          "?" + builtins.concatStringsSep "&" lib.attrsets.mapAttrsToList
-          (k: v: k + "=" + lib.strings.escapeURL v) params
+          "?" + builtins.concatStringsSep "&"
+          (lib.attrsets.mapAttrsToList (k: v: k + "=" + lib.strings.escapeURL v)
+            (lib.attrsets.filterAttrs (k: v: v != null) params))
         else
           "";
 
diff --git a/tests/modules/programs/aerc/default.nix b/tests/modules/programs/aerc/default.nix
index 9417a2197..80b7e9efc 100644
--- a/tests/modules/programs/aerc/default.nix
+++ b/tests/modules/programs/aerc/default.nix
@@ -2,4 +2,5 @@
   aerc-noSettings = ./noSettings.nix;
   aerc-settings = ./settings.nix;
   aerc-assertion = ./assertion.nix;
+  aerc-oauth = ./oauth.nix;
 }
diff --git a/tests/modules/programs/aerc/oauth.expected b/tests/modules/programs/aerc/oauth.expected
new file mode 100644
index 000000000..6824d1fed
--- /dev/null
+++ b/tests/modules/programs/aerc/oauth.expected
@@ -0,0 +1,9 @@
+# Generated by Home Manager.
+
+[basic]
+copy-to = Sent
+default = Inbox
+from = Annie X. Hacker <anniex@mail.invalid>
+outgoing = smtp+xoauth2://anniex@smtp.office365.com:587?client_id=9e5f94bc-e8a4-4e73-b8be-63364c29d753&token_endpoint=https%3A%2F%2Flogin.microsoftonline.com%2Fcommon%2Foauth2%2Fv2.0%2Ftoken
+postpone = Drafts
+source = imaps+xoauth2://anniex@outlook.office365.com:993?client_id=9e5f94bc-e8a4-4e73-b8be-63364c29d753&token_endpoint=https%3A%2F%2Flogin.microsoftonline.com%2Fcommon%2Foauth2%2Fv2.0%2Ftoken
diff --git a/tests/modules/programs/aerc/oauth.nix b/tests/modules/programs/aerc/oauth.nix
new file mode 100644
index 000000000..e91d25203
--- /dev/null
+++ b/tests/modules/programs/aerc/oauth.nix
@@ -0,0 +1,39 @@
+{ config, pkgs, ... }: {
+  config = {
+    nmt.script = let
+      dir = if (pkgs.stdenv.isDarwin && !config.xdg.enable) then
+        "home-files/Library/Preferences/aerc"
+      else
+        "home-files/.config/aerc";
+    in ''
+      assertFileContent ${dir}/accounts.conf ${./oauth.expected}
+    '';
+    programs.aerc = {
+      enable = true;
+      extraConfig.general.unsafe-accounts-conf = true;
+    };
+
+    accounts.email.accounts = {
+      basic = {
+        realName = "Annie X. Hacker";
+        userName = "anniex";
+        address = "anniex@mail.invalid";
+        primary = true;
+        flavor = "outlook.office365.com";
+
+        aerc = rec {
+          enable = true;
+          imapAuth = "xoauth2";
+          smtpAuth = imapAuth;
+          imapOauth2Params = {
+            client_id = "9e5f94bc-e8a4-4e73-b8be-63364c29d753";
+            token_endpoint =
+              "https://login.microsoftonline.com/common/oauth2/v2.0/token";
+          };
+          smtpOauth2Params = imapOauth2Params;
+        };
+      };
+    };
+  };
+}
+