diff --git a/shared/nm-glib-aux/nm-ref-string.c b/shared/nm-glib-aux/nm-ref-string.c
index 526185f3ae..ea8159f0d3 100644
--- a/shared/nm-glib-aux/nm-ref-string.c
+++ b/shared/nm-glib-aux/nm-ref-string.c
@@ -168,24 +168,25 @@ void
 _nm_ref_string_unref_non_null(NMRefString *rstr)
 {
     RefString *const rstr0 = (RefString *) rstr;
+    int              r;
 
     _ASSERT(rstr0);
 
-    if (G_LIKELY(!g_atomic_int_dec_and_test(&rstr0->ref_count)))
+    /* fast-path: first try to decrement the ref-count without bringing it
+     * to zero. */
+    r = rstr0->ref_count;
+    if (G_LIKELY(r > 1 && g_atomic_int_compare_and_exchange(&rstr0->ref_count, r, r - 1)))
         return;
 
+    /* We apparently are about to return the last reference. Take a lock. */
+
     G_LOCK(gl_lock);
 
-    /* in the fast-path above, we already decremented the ref-count to zero.
-     * We need recheck that the ref-count is still zero. */
+    nm_assert(g_hash_table_lookup(gl_hash, rstr0) == rstr0);
 
-    if (g_atomic_int_get(&rstr0->ref_count) == 0) {
+    if (G_LIKELY(g_atomic_int_dec_and_test(&rstr0->ref_count))) {
         if (!g_hash_table_remove(gl_hash, rstr0))
             nm_assert_not_reached();
-    } else {
-#if NM_MORE_ASSERTS > 5
-        nm_assert(g_hash_table_lookup(gl_hash, rstr0) == rstr0);
-#endif
     }
 
     G_UNLOCK(gl_lock);