diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9aa10d9..ba2d5e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # SpamAssassin Milter changelog
 
+## 0.1.5 (unreleased)
+
+*   Properly specify minimal dependency versions in `Cargo.toml`.
+*   Document minimum supported Rust version 1.42.0.
+
 ## 0.1.4 (2020-10-18)
 
 *   Correct a typo in log messages.
diff --git a/Cargo.toml b/Cargo.toml
index 038e5f1..c1d77d4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,9 +11,9 @@ repository = "https://gitlab.com/glts/spamassassin-milter"
 exclude = ["/.gitignore", "/.gitlab-ci.yml"]
 
 [dependencies]
-chrono = "0.4"
-clap = "2"
+chrono = "0.4.10"
+clap = "2.33"
 ipnet = "2.2"
-libc = "0.2"
+libc = "0.2.66"
 milter = "0.2.1"
 once_cell = "1.3"
diff --git a/README.md b/README.md
index c2f703e..b060c72 100644
--- a/README.md
+++ b/README.md
@@ -56,11 +56,12 @@ PKG_CONFIG_PATH=. cargo build
 ```
 
 The integration tests rely on the `miltertest` utility. Make sure `miltertest`
-is available and can be executed when running the integration tests.
+is available and can be executed when running the integration tests. (Until
+recently, `miltertest` had a serious bug that prevents most integration tests in
+this package from completing; make sure you use an up-to-date version of
+`miltertest`.)
 
-Note that until recently `miltertest` had a serious bug that prevents most
-integration tests in this package from completing. Make sure you use an
-up-to-date version of `miltertest`.
+The minimum supported Rust version is 1.42.0.
 
 [Rust]: https://www.rust-lang.org