diff --git a/contrib/guix/INSTALL.md b/contrib/guix/INSTALL.md
index c7050b2ae3..2ab9968bdf 100644
--- a/contrib/guix/INSTALL.md
+++ b/contrib/guix/INSTALL.md
@@ -364,7 +364,7 @@ This is especially notable because Ubuntu Focal packages `libgit2 v0.28.4`, and
 Should you be in this situation, you need to build both `libgit2 v1.1.x` and
 `guile-git` from source.
 
-Source: http://logs.guix.gnu.org/guix/2020-11-12.log#232527
+Source: https://logs.guix.gnu.org/guix/2020-11-12.log#232527
 
 ##### `{scheme,guile}-bytestructures` v1.0.8 and v1.0.9 are broken for Guile v2.2
 
diff --git a/contrib/guix/README.md b/contrib/guix/README.md
index 698deb47ac..23050cec48 100644
--- a/contrib/guix/README.md
+++ b/contrib/guix/README.md
@@ -430,6 +430,6 @@ used.
 If you start `guix-daemon` using an init script, you can edit said script to
 supply this flag.
 
-[b17e]: http://bootstrappable.org/
+[b17e]: https://bootstrappable.org/
 [r12e/source-date-epoch]: https://reproducible-builds.org/docs/source-date-epoch/
 [env-vars-list]: #recognized-environment-variables
diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index ab0783840e..248557919a 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -447,7 +447,7 @@ make cov
 
 Profiling is a good way to get a precise idea of where time is being spent in
 code. One tool for doing profiling on Linux platforms is called
-[`perf`](http://www.brendangregg.com/perf.html), and has been integrated into
+[`perf`](https://www.brendangregg.com/perf.html), and has been integrated into
 the functional test framework. Perf can observe a running process and sample
 (at some frequency) where its execution is.
 
diff --git a/src/test/data/README.md b/src/test/data/README.md
index ee907dff53..cc4d41c75d 100644
--- a/src/test/data/README.md
+++ b/src/test/data/README.md
@@ -8,5 +8,5 @@ License
 
 The data files in this directory are distributed under the MIT software
 license, see the accompanying file COPYING or
-http://www.opensource.org/licenses/mit-license.php.
+https://www.opensource.org/licenses/mit-license.php.
 
diff --git a/test/functional/README.md b/test/functional/README.md
index be46730f9d..12da5d8d7a 100644
--- a/test/functional/README.md
+++ b/test/functional/README.md
@@ -190,5 +190,5 @@ perf report -i /path/to/datadir/send-big-msgs.perf.data.xxxx --stdio | c++filt |
 #### See also:
 
 - [Installing perf](https://askubuntu.com/q/50145)
-- [Perf examples](http://www.brendangregg.com/perf.html)
+- [Perf examples](https://www.brendangregg.com/perf.html)
 - [Hotspot](https://github.com/KDAB/hotspot): a GUI for perf output analysis