diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index b71c752caec..32acc004b24 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3764,6 +3764,7 @@ let
   };
 
   cryptopp = import ../development/libraries/crypto++ {
+    # SIDE-EFFECT WARNING: crypto++-5.6.0 is compiled with "-O2 -march=native -mtune=native".
     inherit fetchurl stdenv unzip libtool;
   };