diff --git a/nixos/modules/config/users-groups.nix b/nixos/modules/config/users-groups.nix
index 7fbbfcec7510..8defa86818ab 100644
--- a/nixos/modules/config/users-groups.nix
+++ b/nixos/modules/config/users-groups.nix
@@ -626,7 +626,7 @@ in {
         then
         ''
           The password hash of user "${name}" may be invalid. You must set a
-          valid hash or the user will be locked out of his account. Please
+          valid hash or the user will be locked out of their account. Please
           check the value of option `users.users."${name}".hashedPassword`.
         ''
         else null
diff --git a/nixos/modules/services/networking/3proxy.nix b/nixos/modules/services/networking/3proxy.nix
index ae8a4958ca96..37a48657c1cc 100644
--- a/nixos/modules/services/networking/3proxy.nix
+++ b/nixos/modules/services/networking/3proxy.nix
@@ -124,7 +124,7 @@ in {
                   <literal>"iponly"</literal>: specifies no authentication. ACLs authorization is used.
                 </para></listitem>
                 <listitem><para>
-                  <literal>"strong"</literal>: authentication by username/password. If user is not registered his access is denied regardless of ACLs.
+                  <literal>"strong"</literal>: authentication by username/password. If user is not registered their access is denied regardless of ACLs.
                 </para></listitem>
               </itemizedlist>
 
diff --git a/nixos/tests/sudo.nix b/nixos/tests/sudo.nix
index 5bbec3d57269..8c38f1b47ef0 100644
--- a/nixos/tests/sudo.nix
+++ b/nixos/tests/sudo.nix
@@ -74,7 +74,7 @@ in
         with subtest("test5 user should not be able to run commands under root"):
             machine.fail("sudo -u test5 sudo -n -u root true")
 
-        with subtest("test5 user should be able to keep his environment"):
+        with subtest("test5 user should be able to keep their environment"):
             machine.succeed("sudo -u test5 sudo -n -E -u test1 true")
 
         with subtest("users in group 'barfoo' should not be able to keep their environment"):
diff --git a/pkgs/applications/audio/pamixer/default.nix b/pkgs/applications/audio/pamixer/default.nix
index 71d852485991..3e2192c04148 100644
--- a/pkgs/applications/audio/pamixer/default.nix
+++ b/pkgs/applications/audio/pamixer/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
     description = "Pulseaudio command line mixer";
     longDescription = ''
       Features:
-        - Get the current volume of the default sink, the default source or a selected one by his id
+        - Get the current volume of the default sink, the default source or a selected one by its id
         - Set the volume for the default sink, the default source or any other device
         - List the sinks
         - List the sources