diff --git a/modules/programs/thunderbird.nix b/modules/programs/thunderbird.nix
index 8b14628a1..c15a946ec 100644
--- a/modules/programs/thunderbird.nix
+++ b/modules/programs/thunderbird.nix
@@ -49,6 +49,11 @@ let
       "mail.identity.id_${id}.fullName" = account.realName;
       "mail.identity.id_${id}.useremail" = address;
       "mail.identity.id_${id}.valid" = true;
+      "mail.identity.id_${id}.htmlSigText" =
+        if account.signature.showSignature == "none" then
+          ""
+        else
+          account.signature.text;
     } // optionalAttrs (account.gpg != null) {
       "mail.identity.id_${id}.attachPgpKey" = false;
       "mail.identity.id_${id}.autoEncryptDrafts" = true;
diff --git a/tests/modules/programs/thunderbird/thunderbird-expected-first.js b/tests/modules/programs/thunderbird/thunderbird-expected-first.js
index 0c5a65a82..a0876893b 100644
--- a/tests/modules/programs/thunderbird/thunderbird-expected-first.js
+++ b/tests/modules/programs/thunderbird/thunderbird-expected-first.js
@@ -12,6 +12,7 @@ user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ec
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.e2etechpref", 0);
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.encryptionpolicy", 0);
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.fullName", "H. M. Test");
+user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.htmlSigText", "signature");
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.is_gnupg_key_id", true);
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.last_entered_external_gnupg_key_id", "ABC");
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.openpgp_key_id", "ABC");
@@ -21,6 +22,7 @@ user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ec
 user_pref("mail.identity.id_8bbcff78f53202c0bfaa490a2068e3e5d6e36872144c659952ecc0ada47d7562.valid", true);
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.autoEncryptDrafts", false);
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.fullName", "H. M. Test Jr.");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.htmlSigText", "");
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.protectSubject", false);
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.smtpServer", "smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.useremail", "hm@example.org");
@@ -30,6 +32,7 @@ user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca
 user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.e2etechpref", 0);
 user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.encryptionpolicy", 0);
 user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.fullName", "H. M. Test");
+user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.htmlSigText", "signature");
 user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.is_gnupg_key_id", true);
 user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.last_entered_external_gnupg_key_id", "ABC");
 user_pref("mail.identity.id_cda3f13b64c1db7d4b58ce07a31304a362d7dcaf14476bfabcca913ae41ada9f.openpgp_key_id", "ABC");
diff --git a/tests/modules/programs/thunderbird/thunderbird-expected-second.js b/tests/modules/programs/thunderbird/thunderbird-expected-second.js
index a7c32fd86..085182cbe 100644
--- a/tests/modules/programs/thunderbird/thunderbird-expected-second.js
+++ b/tests/modules/programs/thunderbird/thunderbird-expected-second.js
@@ -6,6 +6,7 @@ user_pref("mail.account.account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da
 user_pref("mail.accountmanager.accounts", "account_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.autoEncryptDrafts", false);
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.fullName", "H. M. Test Jr.");
+user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.htmlSigText", "");
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.protectSubject", false);
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.smtpServer", "smtp_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc");
 user_pref("mail.identity.id_bcd3ace52bed41febb6cdc2fb1303aebaa573e0d993872da503950901bb6c6fc.useremail", "hm@example.org");
diff --git a/tests/modules/programs/thunderbird/thunderbird.nix b/tests/modules/programs/thunderbird/thunderbird.nix
index 1b0441a1d..f65f80bdf 100644
--- a/tests/modules/programs/thunderbird/thunderbird.nix
+++ b/tests/modules/programs/thunderbird/thunderbird.nix
@@ -17,6 +17,11 @@
         tls.enable = true;
       };
       smtp.port = 456;
+
+      signature = {
+        text = "signature";
+        showSignature = "append";
+      };
     };
 
     hm-account = {