diff -r 1aecddf7e209 -r 5c9ec5a0a4ef src/cx/string.h
--- a/src/cx/string.h	Thu Dec 05 01:54:12 2024 +0100
+++ b/src/cx/string.h	Sat Dec 07 23:59:54 2024 +0100
@@ -313,7 +313,11 @@
  * If \p str already contains a string, the memory will be reallocated and
  * the other strings are appended. Otherwise, new memory is allocated.
  *
- * \note It is guaranteed that there is only one allocation.
+ * If memory allocation fails, the pointer in the returned string will
+ * be \c NULL. Depending on the allocator, \c errno might be set.
+ *
+ * \note It is guaranteed that there is only one allocation for the
+ * resulting string.
  * It is also guaranteed that the returned string is zero-terminated.
  *
  * @param alloc the allocator to use
@@ -337,7 +341,11 @@
  * The resulting string will be allocated by the specified allocator.
  * So developers \em must pass the return value to cx_strfree_a() eventually.
  *
- * \note It is guaranteed that there is only one allocation.
+* If memory allocation fails, the pointer in the returned string will
+ * be \c NULL. Depending on the allocator, \c errno might be set.
+ *
+ * \note It is guaranteed that there is only one allocation for the
+ * resulting string.
  * It is also guaranteed that the returned string is zero-terminated.
  *
  * @param alloc the allocator to use
@@ -354,7 +362,11 @@
  * The resulting string will be allocated by standard \c malloc().
  * So developers \em must pass the return value to cx_strfree() eventually.
  *
- * \note It is guaranteed that there is only one allocation.
+* If memory allocation fails, the pointer in the returned string will
+ * be \c NULL and \c errno might be set.
+ *
+ * \note It is guaranteed that there is only one allocation for the
+ * resulting string.
  * It is also guaranteed that the returned string is zero-terminated.
  *
  * @param count   the number of the other following strings to concatenate
@@ -373,7 +385,11 @@
  * If \p str already contains a string, the memory will be reallocated and
  * the other strings are appended. Otherwise, new memory is allocated.
  *
- * \note It is guaranteed that there is only one allocation.
+* If memory allocation fails, the pointer in the returned string will
+ * be \c NULL and \c errno might be set.
+ *
+ * \note It is guaranteed that there is only one allocation for the
+ * resulting string.
  * It is also guaranteed that the returned string is zero-terminated.
  *
  * @param str     the string the other strings shall be concatenated to