diff --git a/doc/compatibility.rst b/doc/compatibility.rst
index 7d8b10f..e6b59a3 100644
--- a/doc/compatibility.rst
+++ b/doc/compatibility.rst
@@ -49,3 +49,14 @@
     $ openssl rsautl -in testfile.rsa -inkey privatekey.pem -decrypt
     hello there
 
+Interoperability with PKCS#8
+--------------------------------------------------
+
+The standard PKCS#8 is widely used, and more complex than the PKCS#1
+v1.5 supported by Python-RSA. In order to extract a key from the
+PKCS#8 format you need an external tool such as OpenSSL::
+
+    openssl rsa -in privatekey-pkcs8.pem -out privatekey.pem
+
+You can then extract the corresponding public key as described above.
+