diff --git a/README.md b/README.md
index 633955b86..92dec4ffc 100644
--- a/README.md
+++ b/README.md
@@ -54,6 +54,14 @@ Currently Tezos is being developed for Linux only. It should work on mac OS,
 but it has not been tested recently. A Windows port is in progress.
 
 
+Note that, when executing `make build-deps`, OPAM will detect if
+required system dependencies are installed. However, it is not able to
+detect which versions you actually have. Typically, `make` will
+probably fail if you have an libsodium < 1.0.11. In this case, make
+sure you have a recent version of libsodium and libsodium-dev, or
+download and install them from, eg,
+https://pkgs.org/download/libsodium18 and
+https://pkgs.org/download/libsodium-dev
 
 Running the node in a sandbox
 -----------------------------