diff --git a/NEWS b/NEWS
index 50fe61e0..f21b5b0c 100644
--- a/NEWS
+++ b/NEWS
@@ -1,7 +1,11 @@
 dbus 1.14.10 (UNRELEASED)
 =========================
 
-...
+Bug fixes:
+
+• Return the primary group ID in GetConnectionCredentials()' UnixGroupIDs
+  field for processes with a valid-but-empty supplementary group list
+  (dbus!422, cptpcrd)
 
 dbus 1.14.8 (2023-06-06)
 ========================
diff --git a/dbus/dbus-sysdeps-unix.c b/dbus/dbus-sysdeps-unix.c
index 6b32df66..099637cb 100644
--- a/dbus/dbus-sysdeps-unix.c
+++ b/dbus/dbus-sysdeps-unix.c
@@ -1932,6 +1932,8 @@ add_groups_to_credentials (int              client_fd,
 {
 #if defined(__linux__) && defined(SO_PEERGROUPS)
   _DBUS_STATIC_ASSERT (sizeof (gid_t) <= sizeof (dbus_gid_t));
+  /* This function assumes socklen_t is unsigned, which is true on Linux */
+  _DBUS_STATIC_ASSERT (((socklen_t) -1) > 0);
   gid_t *buf = NULL;
   socklen_t len = 1024;
   dbus_bool_t oom = FALSE;
@@ -1977,13 +1979,6 @@ add_groups_to_credentials (int              client_fd,
       _dbus_verbose ("will try again with %lu\n", (unsigned long) len);
     }
 
-  if (len <= 0)
-    {
-      _dbus_verbose ("getsockopt(SO_PEERGROUPS) yielded <= 0 bytes: %ld\n",
-                     (long) len);
-      goto out;
-    }
-
   if (len > n_gids * sizeof (gid_t))
     {
       _dbus_verbose ("%lu > %zu", (unsigned long) len, n_gids * sizeof (gid_t));