diff --git a/src/libsystemd/sd-login/sd-login.c b/src/libsystemd/sd-login/sd-login.c
index 939b2a5df4..70ed8188a2 100644
--- a/src/libsystemd/sd-login/sd-login.c
+++ b/src/libsystemd/sd-login/sd-login.c
@@ -355,7 +355,7 @@ _public_ int sd_uid_is_on_seat(uid_t uid, int require_active, const char *seat)
         char t[DECIMAL_STR_MAX(uid_t)];
         xsprintf(t, UID_FMT, uid);
 
-        return string_contains_word(content, ",", t);
+        return string_contains_word(content, NULL, t);
 }
 
 static int uid_get_array(uid_t uid, const char *variable, char ***array) {