diff --git a/FORK.md b/FORK.md
index 82d5c890..d0f1db37 100644
--- a/FORK.md
+++ b/FORK.md
@@ -192,7 +192,7 @@ Signing is unaffected either way.
 
 - `cargo fmt --all -- --check` — clean.
 - `cargo clippy --all-features --all-targets` — clean.
-- `cargo test --all-features -- --test-threads 1` — 68 unit + 23 integration tests
+- `cargo test --all-features -- --test-threads 1` — 68 unit + 24 integration tests
   pass (10 ignored, all hardware-dependent).
 - The published image is pulled and checked on every release: it reports its own
   version, keeps `tmkms` as the entrypoint, and links the USB libraries the
diff --git a/src/commands/yubihsm/keys/import.rs b/src/commands/yubihsm/keys/import.rs
index 00e96eea..6adf7976 100644
--- a/src/commands/yubihsm/keys/import.rs
+++ b/src/commands/yubihsm/keys/import.rs
@@ -172,9 +172,17 @@ impl ImportCommand {
             })
             .priv_key;
 
+        // `PrivValidatorKey` also accepts secp256k1, so this is reachable with a
+        // legitimate key file
         let seed = match private_key {
             PrivateKey::Ed25519(pk) => pk,
-            _ => unreachable!(),
+            _ => {
+                status_err!(
+                    "unsupported key type in `{}`: an Ed25519 consensus key is required",
+                    self.path.display()
+                );
+                process::exit(1);
+            }
         };
 
         let label = object::Label::from(self.label.as_ref().map(|l| l.as_ref()).unwrap_or(""));
diff --git a/tests/cli/yubihsm.rs b/tests/cli/yubihsm.rs
index 3ea86847..9a459256 100644
--- a/tests/cli/yubihsm.rs
+++ b/tests/cli/yubihsm.rs
@@ -10,6 +10,9 @@ pub const KMS_GNO_PREFIX_CONFIG_PATH: &str = "tests/support/kms_yubihsm_mock_gno
 #[allow(dead_code)]
 pub const PRIV_VALIDATOR_CONFIG_PATH: &str = "tests/support/priv_validator_mock.json";
 
+/// A priv_validator key file holding a secp256k1 key rather than an Ed25519 one
+pub const SECP256K1_PRIV_VALIDATOR_PATH: &str = "tests/support/priv_validator_secp256k1_mock.json";
+
 // This test requires USB access to a YubiHSM2
 #[cfg(not(feature = "yubihsm-mock"))]
 mod detect;
diff --git a/tests/cli/yubihsm/keys.rs b/tests/cli/yubihsm/keys.rs
index a27e8821..21dc0d12 100644
--- a/tests/cli/yubihsm/keys.rs
+++ b/tests/cli/yubihsm/keys.rs
@@ -4,7 +4,7 @@ mod generate;
 mod import;
 mod list;
 
-pub use super::{KMS_CONFIG_PATH, PRIV_VALIDATOR_CONFIG_PATH};
+pub use super::{KMS_CONFIG_PATH, PRIV_VALIDATOR_CONFIG_PATH, SECP256K1_PRIV_VALIDATOR_PATH};
 use crate::cli;
 
 #[test]
diff --git a/tests/cli/yubihsm/keys/import.rs b/tests/cli/yubihsm/keys/import.rs
index 6e0a7272..848e6384 100644
--- a/tests/cli/yubihsm/keys/import.rs
+++ b/tests/cli/yubihsm/keys/import.rs
@@ -3,8 +3,8 @@
 use crate::cli;
 use std::str;
 
-#[test]
-fn keys_import_priv_validator_test() {
+/// Arguments to import the given priv_validator key file as key 0x0001
+fn import_json_args(path: &str) -> Vec<&str> {
     #[allow(unused_mut)]
     let mut args = vec!["yubihsm", "keys", "import"];
 
@@ -12,7 +12,13 @@ fn keys_import_priv_validator_test() {
     args.extend_from_slice(&["-c", super::KMS_CONFIG_PATH]);
     args.extend_from_slice(&["-t", "json"]);
     args.extend_from_slice(&["-i", "1"]); // key ID
-    args.extend_from_slice(&[super::PRIV_VALIDATOR_CONFIG_PATH]);
+    args.push(path);
+    args
+}
+
+#[test]
+fn keys_import_priv_validator_test() {
+    let args = import_json_args(super::PRIV_VALIDATOR_CONFIG_PATH);
 
     let out = cli::run_successfully(args.as_slice());
 
@@ -21,3 +27,24 @@ fn keys_import_priv_validator_test() {
     let message = str::from_utf8(&out.stderr).unwrap().trim().to_owned();
     assert!(message.contains("key 0x0001"));
 }
+
+/// A priv_validator key file can hold a secp256k1 key, which cannot be imported as
+/// an Ed25519 consensus key: that has to be an error the operator can act on, not
+/// a panic
+#[test]
+fn keys_import_rejects_a_secp256k1_priv_validator() {
+    let args = import_json_args(super::SECP256K1_PRIV_VALIDATOR_PATH);
+
+    let out = cli::run(args.as_slice());
+    let message = str::from_utf8(&out.stderr).unwrap();
+
+    assert_eq!(out.status.code(), Some(1), "{message}");
+    assert!(
+        message.contains("Ed25519 consensus key is required"),
+        "{message}"
+    );
+    assert!(
+        message.contains(super::SECP256K1_PRIV_VALIDATOR_PATH),
+        "{message}"
+    );
+}
diff --git a/tests/support/priv_validator_secp256k1_mock.json b/tests/support/priv_validator_secp256k1_mock.json
new file mode 100644
index 00000000..2279a223
--- /dev/null
+++ b/tests/support/priv_validator_secp256k1_mock.json
@@ -0,0 +1,12 @@
+{
+  "comment": "TEST KEY ONLY: DO **NOT** USE!! secp256k1, secret = 32 bytes of 0x01",
+  "address": "79B000887626B294A914501A4CD226B58B235983",
+  "pub_key": {
+    "type": "tendermint/PubKeySecp256k1",
+    "value": "AxuExVZ7EmRAmV0+1aq6BWXXHhg0YEgZ/5wX9enV3QeP"
+  },
+  "priv_key": {
+    "type": "tendermint/PrivKeySecp256k1",
+    "value": "AQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQE="
+  }
+}