diff --git a/chacha20/Cargo.toml b/chacha20/Cargo.toml
index a061739..accb922 100644
--- a/chacha20/Cargo.toml
+++ b/chacha20/Cargo.toml
@@ -23,7 +23,9 @@ cfg-if = "1"
 cipher = { version = "=0.5.0-pre.7", optional = true }
 rand_core = { version = "0.9.0-alpha.2", optional = true, default-features = false }
 serde = { version = "1.0", features = ["derive"], optional = true }
-zeroize = { version = "1.8.1", optional = true }
+
+# `zeroize` is an explicit dependency because this crate may be used without the `cipher` crate
+zeroize = { version = "1.8.1", optional = true, default-features = false }
 
 [target.'cfg(any(target_arch = "x86_64", target_arch = "x86"))'.dependencies]
 cpufeatures = "0.2"