diff --git a/crypto.go b/crypto.go
index a705cdde..558c18cf 100644
--- a/crypto.go
+++ b/crypto.go
@@ -72,6 +72,10 @@ func encodePrivateKey(key crypto.PrivateKey) ([]byte, error) {
 func decodePrivateKey(keyPEMBytes []byte) (crypto.Signer, error) {
 	keyBlockDER, _ := pem.Decode(keyPEMBytes)
 
+	if keyBlockDER == nil {
+		return nil, fmt.Errorf("failed to decode PEM block containing private key")
+	}
+
 	if keyBlockDER.Type != "PRIVATE KEY" && !strings.HasSuffix(keyBlockDER.Type, " PRIVATE KEY") {
 		return nil, fmt.Errorf("unknown PEM header %q", keyBlockDER.Type)
 	}
diff --git a/crypto_test.go b/crypto_test.go
index 71336ef6..e78c85b7 100644
--- a/crypto_test.go
+++ b/crypto_test.go
@@ -44,6 +44,12 @@ func TestEncodeDecodeRSAPrivateKey(t *testing.T) {
 		t.Error("error loading private key:", err)
 	}
 
+	// test load (should fail)
+	_, err = decodePrivateKey(savedBytes[2:])
+	if err == nil {
+		t.Error("loading private key should have failed")
+	}
+
 	// verify loaded key is correct
 	if !privateKeysSame(privateKey, loadedKey) {
 		t.Error("Expected key bytes to be the same, but they weren't")