diff --git a/src/lib.rs b/src/lib.rs
index debf3a0..0de6770 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -151,7 +151,7 @@ where
     ) -> Result {
         info!("PIV responding to {:02x?}", command);
         let parsed_command: Command = command.try_into()?;
-        info!("parsed: {:?}", &parsed_command);
+        info!("parsed: {:02x?}", &parsed_command);
         let reply = Reply(reply);
 
         match parsed_command {
diff --git a/tests/large-cert.der b/tests/large-cert.der
new file mode 100644
index 0000000..01ec76c
Binary files /dev/null and b/tests/large-cert.der differ
diff --git a/tests/large-cert.pem b/tests/large-cert.pem
new file mode 100644
index 0000000..293073a
--- /dev/null
+++ b/tests/large-cert.pem
@@ -0,0 +1,41 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/pivy.rs b/tests/pivy.rs
index ab166c6..3c10127 100644
--- a/tests/pivy.rs
+++ b/tests/pivy.rs
@@ -9,7 +9,8 @@ use card::with_vsc;
 
 use expectrl::{spawn, Eof, Regex, WaitStatus};
 
-use std::io::Write;
+use std::include_str;
+use std::io::{Read, Write};
 use std::process::{Command, Stdio};
 
 #[test_log::test]
@@ -76,3 +77,31 @@ fn ecdh() {
         assert_eq!(p.wait().unwrap().code(), Some(0));
     });
 }
+
+#[test_log::test]
+fn large_cert() {
+    with_vsc(|| {
+        let mut p = Command::new("pivy-tool")
+            .args(["write-cert", "9A"])
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .spawn()
+            .unwrap();
+        let mut stdin = p.stdin.take().unwrap();
+        stdin.write_all(include_bytes!("large-cert.der")).unwrap();
+        drop(stdin);
+        assert_eq!(p.wait().unwrap().code(), Some(0));
+
+        let mut p = Command::new("pivy-tool")
+            .args(["cert", "9A"])
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .spawn()
+            .unwrap();
+        let mut stdout = p.stdout.take().unwrap();
+        let mut buf = String::new();
+        stdout.read_to_string(&mut buf).unwrap();
+        assert_eq!(buf, include_str!("large-cert.pem"));
+        assert_eq!(p.wait().unwrap().code(), Some(0));
+    });
+}