diff --git a/Cargo.lock b/Cargo.lock
index 2c4093ce..069c734e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -119,9 +119,9 @@ dependencies = [
 
 [[package]]
 name = "base64"
-version = "0.21.4"
+version = "0.21.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ba43ea6f343b788c8764558649e08df62f86c6ef251fdaeb1ffd010a9ae50a2"
+checksum = "35636a1494ede3b646cc98f74f8e62c773a38a659ebc777a2cf26b9b74171df9"
 
 [[package]]
 name = "bitflags"
diff --git a/Cargo.toml b/Cargo.toml
index ac72795e..179e9512 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,7 +15,7 @@ aes = { version = "0.8.3", optional = true }
 bitvec = { version = "1.0.1", optional = true }
 ctr = { version = "0.9.2", optional = true }
 cmac = { version = "0.7.2", optional = true }
-base64 = "0.21.4"
+base64 = "0.21.5"
 byteorder = "1.5.0"
 fiat-crypto = { version = "0.2.1", optional = true }
 fixed = { version = "1.23", optional = true }
diff --git a/binaries/Cargo.toml b/binaries/Cargo.toml
index b6749107..2bd00f28 100644
--- a/binaries/Cargo.toml
+++ b/binaries/Cargo.toml
@@ -7,7 +7,7 @@ license = "MPL-2.0"
 repository = "https://github.com/divviup/libprio-rs"
 
 [dependencies]
-base64 = "0.21.4"
+base64 = "0.21.5"
 color-eyre = { version = "^0.6" }
 fixed-macro = "1.2.0"
 prio = { path = "..", features = ["test-util", "prio2", "experimental", "multithreaded"] }
diff --git a/supply-chain/audits.toml b/supply-chain/audits.toml
index 92ab7b8a..7d87ccc3 100644
--- a/supply-chain/audits.toml
+++ b/supply-chain/audits.toml
@@ -55,6 +55,11 @@ who = "Ameer Ghani <inahga@divviup.org>"
 criteria = "safe-to-deploy"
 delta = "0.21.3 -> 0.21.4"
 
+[[audits.base64]]
+who = "David Cook <dcook@divviup.org>"
+criteria = "safe-to-deploy"
+delta = "0.21.4 -> 0.21.5"
+
 [[audits.block-buffer]]
 who = "David Cook <dcook@divviup.org>"
 criteria = "safe-to-deploy"