diff --git a/Developer-guides.md b/Developer-guides.md
index 0a59892..f8a0fdd 100644
--- a/Developer-guides.md
+++ b/Developer-guides.md
@@ -97,6 +97,10 @@ Unsupported characters in file names will be replaced by `?`. Operations on file
 
 Disable notifications on `cp`, `mv`, `rm` completion, selection sync to system clipboard and xterm title advertisement on directory change.
 
+#### Compile-in Alexey Tourbin's QSORT
+
+    make O_QSORT=1
+
 #### Compile-in 8 contexts
 
     make O_CTX8=1