diff --git a/docs/KNOWN_BUGS b/docs/KNOWN_BUGS
index 92b92ff5d..c8a757e19 100644
--- a/docs/KNOWN_BUGS
+++ b/docs/KNOWN_BUGS
@@ -3,6 +3,11 @@ join in and help us correct one or more of these! Also be sure to check the
 changelog of the current development status, as one or more of these problems
 may have been fixed since this was written!
 
+76. The SOCKET type in Win64 is 64 bits large (and thus so is curl_socket_t on
+  that platform), and long is only 32 bits. It makes it impossible for
+  curl_easy_getinfo() to return a socket properly with the CURLINFO_LASTSOCKET
+  option as for all other operating systems.
+
 75. NTLM authentication involving unicode user name or password.
   http://curl.haxx.se/mail/lib-2009-10/0024.html
   http://curl.haxx.se/bug/view.cgi?id=2944325
diff --git a/docs/libcurl/curl_easy_getinfo.3 b/docs/libcurl/curl_easy_getinfo.3
index b80eacf7d..9f298ed71 100644
--- a/docs/libcurl/curl_easy_getinfo.3
+++ b/docs/libcurl/curl_easy_getinfo.3
@@ -198,6 +198,9 @@ working with the socket, you must call curl_easy_cleanup() as usual and let
 libcurl close the socket and cleanup other resources associated with the
 handle. This is typically used in combination with \fICURLOPT_CONNECT_ONLY\fP.
 (Added in 7.15.2)
+
+NOTE: this API is not really working on win64, since the SOCKET type on win64
+is 64 bit large while its 'long' is only 32 bits.
 .IP CURLINFO_FTP_ENTRY_PATH
 Pass a pointer to a char pointer to receive a pointer to a string holding the
 path of the entry path. That is the initial path libcurl ended up in when