Add the --disable-experimental option.
diff --git a/INSTALL b/INSTALL
index 92cd085..c0ae106 100644
--- a/INSTALL
+++ b/INSTALL
@@ -116,6 +116,9 @@
     Disable support for junk/zero filling of memory.  See the "opt.junk"/
     "opt.zero" option documentation for usage details.
 
+--disable-experimental
+    Disable support for the experimental API (*allocm()).
+
 --enable-xmalloc
     Enable support for optional immediate termination due to out-of-memory
     errors, as is commonly implemented by "xmalloc" wrapper function for malloc.