diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index e2e54e13d39..d41543ab1c5 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -941,7 +941,9 @@ Threads and synchronization
     internal to a class (private or protected) rather than public.
 
   - Combine annotations in function declarations with run-time asserts in
-    function definitions:
+    function definitions (`AssertLockNotHeld()` can be omitted if `LOCK()` is
+    called unconditionally after it because `LOCK()` does the same check as
+    `AssertLockNotHeld()` internally, for non-recursive mutexes):
 
 ```C++
 // txmempool.h