diff --git a/changes/bug25664 b/changes/bug25664
new file mode 100644
index 000000000..c8b3ca618
--- /dev/null
+++ b/changes/bug25664
@@ -0,0 +1,3 @@
+  o New system requirements:
+    - When built with Rust, Tor now depends on version 0.2.39 of the libc
+      crate. Closes tickets 25310 and 25664.
diff --git a/configure.ac b/configure.ac
index 6c6add187..2b9bc8595 100644
--- a/configure.ac
+++ b/configure.ac
@@ -275,7 +275,7 @@ fi
 AM_CONDITIONAL(USEPYTHON, [test "x$PYTHON" != "x"])
 
 dnl List all external rust crates we depend on here. Include the version
-rust_crates="libc-0.2.22"
+rust_crates="libc-0.2.39"
 AC_SUBST(rust_crates)
 
 ifdef([AC_C_FLEXIBLE_ARRAY_MEMBER], [
diff --git a/doc/HACKING/GettingStartedRust.md b/doc/HACKING/GettingStartedRust.md
index f5914bc87..a533ba8a2 100644
--- a/doc/HACKING/GettingStartedRust.md
+++ b/doc/HACKING/GettingStartedRust.md
@@ -65,7 +65,7 @@ fetching dependencies from Cargo or specifying a local directory.
 
 You'll need the following Rust dependencies (as of this writing):
 
-    libc==0.2.22
+    libc==0.2.39
 
 We vendor our Rust dependencies in a separate repo using
 [cargo-vendor](https://github.com/alexcrichton/cargo-vendor).  To use