diff -r 2fc1c25441f1 -r 7763892ed801 docs/Writerside/topics/string.h.md
--- a/docs/Writerside/topics/string.h.md	Tue May 27 22:31:06 2025 +0200
+++ b/docs/Writerside/topics/string.h.md	Sun Jun 01 16:00:16 2025 +0200
@@ -53,7 +53,7 @@
 ```
 
 The functions `cx_str()` and `cx_mutstr()` create a UCX string from a `const char*` or a `char*`
-and compute the length with a call to stdlib `strlen()`.
+and compute the length with a call to stdlib `strlen()` (except for `NULL` in which case the length is set to zero).
 In case you already know the length, or the string is not zero-terminated, you can use `cx_strn()` or `cx_mutstrn()`.
 
 The function `cx_strdup_a()` allocates new memory with the given `allocator` and copies the given `string`