diff --git a/Cargo.lock b/Cargo.lock
index dbb90d3..1eab04d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -51,7 +51,6 @@ dependencies = [
  "age-plugin",
  "base64",
  "bech32",
- "chrono",
  "console",
  "dialoguer",
  "env_logger",
diff --git a/Cargo.toml b/Cargo.toml
index 67f00e4..0849b1c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -26,7 +26,6 @@ age-core = "0.5"
 age-plugin = "0.0"
 base64 = "0.13"
 bech32 = "0.8"
-chrono = "0.4"
 console = "0.14"
 dialoguer = "0.8"
 env_logger = "0.8"
diff --git a/src/builder.rs b/src/builder.rs
index 2176fe0..f4aff2d 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -123,7 +123,7 @@ impl IdentityBuilder {
             .name
             .unwrap_or(format!("age identity {}", hex::encode(stub.tag)));
 
-        Certificate::generate_self_signed(
+        let cert = Certificate::generate_self_signed(
             yubikey,
             SlotId::Retired(slot),
             serial,
@@ -140,10 +140,13 @@ impl IdentityBuilder {
             )],
         )?;
 
+        let (_, cert) = x509_parser::parse_x509_certificate(cert.as_ref()).unwrap();
+        let created = cert.validity().not_before.to_rfc2822();
+
         Ok((
             Stub::new(yubikey.serial(), slot, &recipient),
             recipient,
-            chrono::Local::now().to_rfc3339_opts(chrono::SecondsFormat::Secs, true),
+            created,
         ))
     }
 }