Use correct, not American spelling.
diff --git a/ssl/ssltest.c b/ssl/ssltest.c
index 2d6c849..efdfd48 100644
--- a/ssl/ssltest.c
+++ b/ssl/ssltest.c
@@ -503,7 +503,7 @@
 		 * Useful functions for querying the state of BIO pair endpoints:
 		 *
 		 * BIO_ctrl_pending(bio)              number of bytes we can read now
-		 * BIO_ctrl_get_read_request(bio)     number of bytes needed to fulfill
+		 * BIO_ctrl_get_read_request(bio)     number of bytes needed to fulfil
 		 *                                      other side's read attempt
 		 * BIO_ctrl_get_write_guarantee(bio)   number of bytes we can write now
 		 *