diff -Naur libsodium-1.0.18-orig/configure.ac libsodium-1.0.18/configure.ac
--- libsodium-1.0.18-orig/configure.ac	2019-05-30 16:20:24.000000000 -0400
+++ libsodium-1.0.18/configure.ac	2021-08-11 08:09:54.653907245 -0400
@@ -217,11 +217,6 @@
 
 AC_CHECK_DEFINE([__wasi__], [WASI="yes"], [])
 
-AC_CHECK_DEFINE([_FORTIFY_SOURCE], [], [
-  AX_CHECK_COMPILE_FLAG([-D_FORTIFY_SOURCE=2],
-    [CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2"])
-])
-
 AX_CHECK_COMPILE_FLAG([-fvisibility=hidden],
   [CFLAGS="$CFLAGS -fvisibility=hidden"])