diff --git a/crypto/jitterentropy.c b/crypto/jitterentropy.c
index ee2aa0b7aa9e24ef23f674bf8d38b69f858a798d..d7056de8c0d7b22981a719f19dcfe8586c80ff24 100644
--- a/crypto/jitterentropy.c
+++ b/crypto/jitterentropy.c
@@ -157,7 +157,7 @@ struct rand_data {
 /*
  * See the SP 800-90B comment #10b for the corrected cutoff for the SP 800-90B
  * APT.
- * http://www.untruth.org/~josh/sp80090b/UL%20SP800-90B-final%20comments%20v1.9%2020191212.pdf
+ * https://www.untruth.org/~josh/sp80090b/UL%20SP800-90B-final%20comments%20v1.9%2020191212.pdf
  * In the syntax of R, this is C = 2 + qbinom(1 − 2^(−30), 511, 2^(-1/osr)).
  * (The original formula wasn't correct because the first symbol must
  * necessarily have been observed, so there is no chance of observing 0 of these