diff --git a/changelog.d/18689.misc b/changelog.d/18689.misc
new file mode 100644
index 0000000000..51f0586e19
--- /dev/null
+++ b/changelog.d/18689.misc
@@ -0,0 +1 @@
+Fix dirty `Cargo.lock` changes appearing after install (`base64`).
diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 4f5ebb68b7..ab87de33ab 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -23,7 +23,7 @@ name = "synapse.synapse_rust"
 
 [dependencies]
 anyhow = "1.0.63"
-base64 = "0.21.7"
+base64 = "0.22.1"
 bytes = "1.6.0"
 headers = "0.4.0"
 http = "1.1.0"