diff --git a/README.adoc b/README.adoc
index d4f8a34..da61cca 100644
--- a/README.adoc
+++ b/README.adoc
@@ -12569,6 +12569,8 @@ which is `4Gib * sizeof(int) == 16GiB`, but these fail at 32GiB:
 ./userland/linux/mmap_anonymous.out 0x200000000
 ....
 
+`malloc` returns NULL, and `mmap` goes a bit further and segfauls on the first assignment `array[0] = 1`.
+
 Bibliography: https://stackoverflow.com/questions/2798330/maximum-memory-which-malloc-can-allocate
 
 ==== GCC C extensions