diff --git a/src/sftp.c b/src/sftp.c
index 95b58026..8d002257 100644
--- a/src/sftp.c
+++ b/src/sftp.c
@@ -716,6 +716,13 @@ static LIBSSH2_SFTP *sftp_init(LIBSSH2_SESSION *session)
 LIBSSH2_API LIBSSH2_SFTP *libssh2_sftp_init(LIBSSH2_SESSION *session)
 {
     LIBSSH2_SFTP *ptr;
+
+    if(!(session->state & LIBSSH2_STATE_AUTHENTICATED)) {
+        _libssh2_error(session, LIBSSH2_ERROR_INVAL,
+                       "session not authenticated yet");
+        return NULL;
+    }
+
     BLOCK_ADJUST_ERRNO(ptr, session, sftp_init(session));
     return ptr;
 }