diff --git a/nixos/tests/shadow.nix b/nixos/tests/shadow.nix
index c51961e1fc68..dd2a575b1935 100644
--- a/nixos/tests/shadow.nix
+++ b/nixos/tests/shadow.nix
@@ -36,9 +36,9 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
 
     with subtest("Normal login"):
         shadow.send_key("alt-f2")
-        shadow.wait_until_succeeds(f"[ $(fgconsole) = 2 ]")
-        shadow.wait_for_unit(f"getty@tty2.service")
-        shadow.wait_until_succeeds(f"pgrep -f 'agetty.*tty2'")
+        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.send_chars("emma\n")
         shadow.wait_until_tty_matches(2, "login: emma")
@@ -60,9 +60,9 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
 
     with subtest("Change password"):
         shadow.send_key("alt-f3")
-        shadow.wait_until_succeeds(f"[ $(fgconsole) = 3 ]")
-        shadow.wait_for_unit(f"getty@tty3.service")
-        shadow.wait_until_succeeds(f"pgrep -f 'agetty.*tty3'")
+        shadow.wait_until_succeeds("[ $(fgconsole) = 3 ]")
+        shadow.wait_for_unit("getty@tty3.service")
+        shadow.wait_until_succeeds("pgrep -f 'agetty.*tty3'")
         shadow.wait_until_tty_matches(3, "login: ")
         shadow.send_chars("emma\n")
         shadow.wait_until_tty_matches(3, "login: emma")
@@ -78,9 +78,9 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
         shadow.send_chars("${password3}\n")
         shadow.sleep(2)
         shadow.send_key("alt-f4")
-        shadow.wait_until_succeeds(f"[ $(fgconsole) = 4 ]")
-        shadow.wait_for_unit(f"getty@tty4.service")
-        shadow.wait_until_succeeds(f"pgrep -f 'agetty.*tty4'")
+        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.send_chars("emma\n")
         shadow.wait_until_tty_matches(4, "login: emma")
@@ -106,9 +106,9 @@ in import ./make-test-python.nix ({ pkgs, ... }: {
 
     with subtest("nologin shell"):
         shadow.send_key("alt-f5")
-        shadow.wait_until_succeeds(f"[ $(fgconsole) = 5 ]")
-        shadow.wait_for_unit(f"getty@tty5.service")
-        shadow.wait_until_succeeds(f"pgrep -f 'agetty.*tty5'")
+        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.send_chars("layla\n")
         shadow.wait_until_tty_matches(5, "login: layla")