diff --git a/nixos/lib/test-driver/test_driver/machine.py b/nixos/lib/test-driver/test_driver/machine.py
index 035e3ffe897..3ff3cf5645f 100644
--- a/nixos/lib/test-driver/test_driver/machine.py
+++ b/nixos/lib/test-driver/test_driver/machine.py
@@ -682,7 +682,7 @@ class Machine:
         with self.nested("waiting for {} to appear on tty {}".format(regexp, tty)):
             retry(tty_matches)
 
-    def send_chars(self, chars: List[str]) -> None:
+    def send_chars(self, chars: str) -> None:
         with self.nested("sending keys ‘{}‘".format(chars)):
             for char in chars:
                 self.send_key(char)
diff --git a/nixos/tests/ecryptfs.nix b/nixos/tests/ecryptfs.nix
index e3cfb2ed998..1c67d307a00 100644
--- a/nixos/tests/ecryptfs.nix
+++ b/nixos/tests/ecryptfs.nix
@@ -11,16 +11,16 @@ import ./make-test-python.nix ({ ... }:
 
   testScript = ''
     def login_as_alice():
-        machine.wait_until_tty_matches(1, "login: ")
+        machine.wait_until_tty_matches("1", "login: ")
         machine.send_chars("alice\n")
-        machine.wait_until_tty_matches(1, "Password: ")
+        machine.wait_until_tty_matches("1", "Password: ")
         machine.send_chars("foobar\n")
-        machine.wait_until_tty_matches(1, "alice\@machine")
+        machine.wait_until_tty_matches("1", "alice\@machine")
 
 
     def logout():
         machine.send_chars("logout\n")
-        machine.wait_until_tty_matches(1, "login: ")
+        machine.wait_until_tty_matches("1", "login: ")
 
 
     machine.wait_for_unit("default.target")
@@ -36,7 +36,7 @@ import ./make-test-python.nix ({ ... }:
     with subtest("Log alice in (ecryptfs passwhrase is wrapped during first login)"):
         login_as_alice()
         machine.send_chars("logout\n")
-        machine.wait_until_tty_matches(1, "login: ")
+        machine.wait_until_tty_matches("1", "login: ")
 
     # Why do I need to do this??
     machine.succeed("su alice -c ecryptfs-umount-private || true")
diff --git a/nixos/tests/login.nix b/nixos/tests/login.nix
index 0d6f81b1721..2cff38d2005 100644
--- a/nixos/tests/login.nix
+++ b/nixos/tests/login.nix
@@ -29,11 +29,11 @@ import ./make-test-python.nix ({ pkgs, latestKernel ? false, ... }:
           machine.wait_until_succeeds("pgrep -f 'agetty.*tty2'")
 
       with subtest("Log in as alice on a virtual console"):
-          machine.wait_until_tty_matches(2, "login: ")
+          machine.wait_until_tty_matches("2", "login: ")
           machine.send_chars("alice\n")
-          machine.wait_until_tty_matches(2, "login: alice")
+          machine.wait_until_tty_matches("2", "login: alice")
           machine.wait_until_succeeds("pgrep login")
-          machine.wait_until_tty_matches(2, "Password: ")
+          machine.wait_until_tty_matches("2", "Password: ")
           machine.send_chars("foobar\n")
           machine.wait_until_succeeds("pgrep -u alice bash")
           machine.send_chars("touch done\n")
diff --git a/nixos/tests/pam/pam-oath-login.nix b/nixos/tests/pam/pam-oath-login.nix
index c532e81e674..dd6ef4a0abc 100644
--- a/nixos/tests/pam/pam-oath-login.nix
+++ b/nixos/tests/pam/pam-oath-login.nix
@@ -77,28 +77,28 @@ in
     machine.screenshot("postboot")
 
     with subtest("Invalid password"):
-        switch_to_tty(2)
-        enter_user_alice(2)
+        switch_to_tty("2")
+        enter_user_alice("2")
 
         machine.send_chars("${oathSnakeOilPassword1}\n")
-        machine.wait_until_tty_matches(2, "Password: ")
+        machine.wait_until_tty_matches("2", "Password: ")
         machine.send_chars("blorg\n")
-        machine.wait_until_tty_matches(2, "Login incorrect")
+        machine.wait_until_tty_matches("2", "Login incorrect")
 
     with subtest("Invalid oath token"):
-        switch_to_tty(3)
-        enter_user_alice(3)
+        switch_to_tty("3")
+        enter_user_alice("3")
 
         machine.send_chars("000000\n")
-        machine.wait_until_tty_matches(3, "Login incorrect")
-        machine.wait_until_tty_matches(3, "login:")
+        machine.wait_until_tty_matches("3", "Login incorrect")
+        machine.wait_until_tty_matches("3", "login:")
 
     with subtest("Happy path: Both passwords are mandatory to get us in"):
-        switch_to_tty(4)
-        enter_user_alice(4)
+        switch_to_tty("4")
+        enter_user_alice("4")
 
         machine.send_chars("${oathSnakeOilPassword2}\n")
-        machine.wait_until_tty_matches(4, "Password: ")
+        machine.wait_until_tty_matches("4", "Password: ")
         machine.send_chars("${alicePassword}\n")
 
         machine.wait_until_succeeds("pgrep -u alice bash")
diff --git a/nixos/tests/shadow.nix b/nixos/tests/shadow.nix
index dd2a575b193..50a9f712464 100644
--- a/nixos/tests/shadow.nix
+++ b/nixos/tests/shadow.nix
@@ -39,9 +39,9 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
         shadow.wait_until_succeeds("[ $(fgconsole) = 2 ]")
         shadow.wait_for_unit("getty@tty2.service")
         shadow.wait_until_succeeds("pgrep -f 'agetty.*tty2'")
-        shadow.wait_until_tty_matches(2, "login: ")
+        shadow.wait_until_tty_matches("2", "login: ")
         shadow.send_chars("emma\n")
-        shadow.wait_until_tty_matches(2, "login: emma")
+        shadow.wait_until_tty_matches("2", "login: emma")
         shadow.wait_until_succeeds("pgrep login")
         shadow.sleep(2)
         shadow.send_chars("${password1}\n")
@@ -63,9 +63,9 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
         shadow.wait_until_succeeds("[ $(fgconsole) = 3 ]")
         shadow.wait_for_unit("getty@tty3.service")
         shadow.wait_until_succeeds("pgrep -f 'agetty.*tty3'")
-        shadow.wait_until_tty_matches(3, "login: ")
+        shadow.wait_until_tty_matches("3", "login: ")
         shadow.send_chars("emma\n")
-        shadow.wait_until_tty_matches(3, "login: emma")
+        shadow.wait_until_tty_matches("3", "login: emma")
         shadow.wait_until_succeeds("pgrep login")
         shadow.sleep(2)
         shadow.send_chars("${password1}\n")
@@ -81,16 +81,16 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
         shadow.wait_until_succeeds("[ $(fgconsole) = 4 ]")
         shadow.wait_for_unit("getty@tty4.service")
         shadow.wait_until_succeeds("pgrep -f 'agetty.*tty4'")
-        shadow.wait_until_tty_matches(4, "login: ")
+        shadow.wait_until_tty_matches("4", "login: ")
         shadow.send_chars("emma\n")
-        shadow.wait_until_tty_matches(4, "login: emma")
+        shadow.wait_until_tty_matches("4", "login: emma")
         shadow.wait_until_succeeds("pgrep login")
         shadow.sleep(2)
         shadow.send_chars("${password1}\n")
-        shadow.wait_until_tty_matches(4, "Login incorrect")
-        shadow.wait_until_tty_matches(4, "login:")
+        shadow.wait_until_tty_matches("4", "Login incorrect")
+        shadow.wait_until_tty_matches("4", "login:")
         shadow.send_chars("emma\n")
-        shadow.wait_until_tty_matches(4, "login: emma")
+        shadow.wait_until_tty_matches("4", "login: emma")
         shadow.wait_until_succeeds("pgrep login")
         shadow.sleep(2)
         shadow.send_chars("${password3}\n")
@@ -109,11 +109,11 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
         shadow.wait_until_succeeds("[ $(fgconsole) = 5 ]")
         shadow.wait_for_unit("getty@tty5.service")
         shadow.wait_until_succeeds("pgrep -f 'agetty.*tty5'")
-        shadow.wait_until_tty_matches(5, "login: ")
+        shadow.wait_until_tty_matches("5", "login: ")
         shadow.send_chars("layla\n")
-        shadow.wait_until_tty_matches(5, "login: layla")
+        shadow.wait_until_tty_matches("5", "login: layla")
         shadow.wait_until_succeeds("pgrep login")
         shadow.send_chars("${password2}\n")
-        shadow.wait_until_tty_matches(5, "login:")
+        shadow.wait_until_tty_matches("5", "login:")
   '';
 })
diff --git a/nixos/tests/sway.nix b/nixos/tests/sway.nix
index 8f95f2a030d..52e2c7c99ec 100644
--- a/nixos/tests/sway.nix
+++ b/nixos/tests/sway.nix
@@ -4,6 +4,12 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
     maintainers = with lib.maintainers; [ primeos synthetica ];
   };
 
+  # testScriptWithTypes:49: error: Cannot call function of unknown type
+  #           (machine.succeed if succeed else machine.execute)(
+  #           ^
+  # Found 1 error in 1 file (checked 1 source file)
+  skipTypeCheck = true;
+
   nodes.machine = { config, ... }: {
     # Automatically login on tty1 as a normal user:
     imports = [ ./common/user-account.nix ];
diff --git a/nixos/tests/uptermd.nix b/nixos/tests/uptermd.nix
index d504ef06419..429e3c9dd5f 100644
--- a/nixos/tests/uptermd.nix
+++ b/nixos/tests/uptermd.nix
@@ -42,7 +42,7 @@ in
 
     client1.wait_for_unit("multi-user.target")
     client1.wait_until_succeeds("pgrep -f 'agetty.*tty1'")
-    client1.wait_until_tty_matches(1, "login: ")
+    client1.wait_until_tty_matches("1", "login: ")
     client1.send_chars("root\n")
     client1.wait_until_succeeds("pgrep -u root bash")
 
diff --git a/nixos/tests/user-activation-scripts.nix b/nixos/tests/user-activation-scripts.nix
index 93457357818..5df072ce050 100644
--- a/nixos/tests/user-activation-scripts.nix
+++ b/nixos/tests/user-activation-scripts.nix
@@ -19,9 +19,9 @@ import ./make-test-python.nix ({ lib, ... }: {
 
     machine.wait_for_unit("multi-user.target")
     machine.wait_for_unit("getty@tty1.service")
-    machine.wait_until_tty_matches(1, "login: ")
+    machine.wait_until_tty_matches("1", "login: ")
     machine.send_chars("alice\n")
-    machine.wait_until_tty_matches(1, "Password: ")
+    machine.wait_until_tty_matches("1", "Password: ")
     machine.send_chars("pass1\n")
     machine.send_chars("touch login-ok\n")
     machine.wait_for_file("/home/alice/login-ok")
diff --git a/nixos/tests/user-home-mode.nix b/nixos/tests/user-home-mode.nix
index 1366d102a99..070cb0b75cc 100644
--- a/nixos/tests/user-home-mode.nix
+++ b/nixos/tests/user-home-mode.nix
@@ -17,9 +17,9 @@ import ./make-test-python.nix ({ lib, ... }: {
   testScript = ''
     machine.wait_for_unit("multi-user.target")
     machine.wait_for_unit("getty@tty1.service")
-    machine.wait_until_tty_matches(1, "login: ")
+    machine.wait_until_tty_matches("1", "login: ")
     machine.send_chars("alice\n")
-    machine.wait_until_tty_matches(1, "Password: ")
+    machine.wait_until_tty_matches("1", "Password: ")
     machine.send_chars("pass1\n")
     machine.succeed('[ "$(stat -c %a /home/alice)" == "700" ]')
     machine.succeed('[ "$(stat -c %a /home/bob)" == "750" ]')
diff --git a/nixos/tests/zsh-history.nix b/nixos/tests/zsh-history.nix
index 35568779840..64f32a07e21 100644
--- a/nixos/tests/zsh-history.nix
+++ b/nixos/tests/zsh-history.nix
@@ -21,13 +21,13 @@ import ./make-test-python.nix ({ pkgs, ...} : {
     default.wait_until_succeeds("pgrep -f 'agetty.*tty1'")
 
     # Login
-    default.wait_until_tty_matches(1, "login: ")
+    default.wait_until_tty_matches("1", "login: ")
     default.send_chars("root\n")
-    default.wait_until_tty_matches(1, r"\nroot@default\b")
+    default.wait_until_tty_matches("1", r"\nroot@default\b")
 
     # Generate some history
     default.send_chars("echo foobar\n")
-    default.wait_until_tty_matches(1, "foobar")
+    default.wait_until_tty_matches("1", "foobar")
 
     # Ensure that command was recorded in history
     default.succeed("/run/current-system/sw/bin/history list | grep -q foobar")