diff --git a/docs/INSTALL.rst b/docs/INSTALL.rst
index 7800b55..7f291d0 100644
--- a/docs/INSTALL.rst
+++ b/docs/INSTALL.rst
@@ -51,6 +51,11 @@
 
        sudo port install pkgconfig boost sqlite3 libcryptopp
 
+   .. note::
+
+      If a major OS X system upgrade is performed after installing dependencies with MacPorts,
+      remember to `reinstall all ports <https://trac.macports.org/wiki/Migration>`__.
+
 -  Ubuntu
 
    In a terminal, enter::