diff --git a/shared/nm-glib-aux/nm-macros-internal.h b/shared/nm-glib-aux/nm-macros-internal.h
index 52591040e2..3cb11a973f 100644
--- a/shared/nm-glib-aux/nm-macros-internal.h
+++ b/shared/nm-glib-aux/nm-macros-internal.h
@@ -1023,6 +1023,24 @@ nm_str_realloc (char *str)
 #define nm_assert_not_reached() G_STMT_START { ; } G_STMT_END
 #endif
 
+/* Usage:
+ *
+ *   if (NM_MORE_ASSERT_ONCE (5)) { extra_check (); }
+ *
+ * This will only run the check once, and only if NM_MORE_ASSERT is >= than
+ * more_assert_level.
+ */
+#define NM_MORE_ASSERT_ONCE(more_assert_level) \
+	(   (NM_MORE_ASSERTS >= (more_assert_level)) \
+	 && ({ \
+	        static volatile int _assert_once = 0; \
+	        \
+	        G_STATIC_ASSERT_EXPR ((more_assert_level) >= 0); \
+	        \
+	        G_UNLIKELY (   _assert_once == 0 \
+	                    && g_atomic_int_compare_and_exchange (&_assert_once, 0, 1)); \
+	    }))
+
 /*****************************************************************************/
 
 #define NM_GOBJECT_PROPERTIES_DEFINE_BASE(...) \