diff --git a/src/data_model/ta.rs b/src/data_model/ta.rs
index 197b47d..826979d 100644
--- a/src/data_model/ta.rs
+++ b/src/data_model/ta.rs
@@ -244,6 +244,9 @@ pub enum TrustAnchorError {
     #[error("TA certificate error: {0} (RFC 8630 §2.3)")]
     TaCertificate(#[from] TaCertificateDecodeError),
 
+    #[error("TA certificate self-signature error: {0} (RFC 8630 §2.3)")]
+    TaSelfSignature(#[from] TaCertificateVerifyError),
+
     #[error("{0}")]
     Bind(#[from] TrustAnchorBindError),
 }
@@ -269,6 +272,7 @@ impl TrustAnchor {
         resolved_uri: Option<&Url>,
     ) -> Result<Self, TrustAnchorError> {
         let ta_certificate = TaCertificate::decode_der(ta_der)?;
+        ta_certificate.verify_self_signature()?;
         Ok(Self::bind(tal, ta_certificate, resolved_uri)?)
     }
 
@@ -278,6 +282,7 @@ impl TrustAnchor {
         resolved_uri: Option<&Url>,
     ) -> Result<Self, TrustAnchorError> {
         let ta_certificate = TaCertificate::decode_der_with_strict_name(ta_der)?;
+        ta_certificate.verify_self_signature()?;
         Ok(Self::bind(tal, ta_certificate, resolved_uri)?)
     }
 
diff --git a/tests/test_from_tal_offline.rs b/tests/test_from_tal_offline.rs
index 1cdbba4..1e58292 100644
--- a/tests/test_from_tal_offline.rs
+++ b/tests/test_from_tal_offline.rs
@@ -88,6 +88,18 @@ fn offline_discovery_from_apnic_tal_and_ta_der_fixture_works() {
     }
 }
 
+#[test]
+fn offline_discovery_rejects_tampered_ta_self_signature() {
+    let tal_bytes = apnic_tal_bytes();
+    let mut ta_der = apnic_ta_der();
+    let last = ta_der.last_mut().expect("TA fixture must not be empty");
+    *last ^= 0x01;
+
+    let err = discover_root_ca_instance_from_tal_and_ta_der(&tal_bytes, &ta_der, None)
+        .expect_err("tampered TA signature must not form a root CA instance");
+    assert!(err.to_string().contains("self-signature"), "{err}");
+}
+
 #[test]
 fn discover_root_from_tal_url_works_with_mock_fetcher() {
     let tal_bytes = apnic_tal_bytes();
diff --git a/tests/test_trust_anchor_bind.rs b/tests/test_trust_anchor_bind.rs
index 7adc99b..3400725 100644
--- a/tests/test_trust_anchor_bind.rs
+++ b/tests/test_trust_anchor_bind.rs
@@ -1,4 +1,6 @@
-use rpki::data_model::ta::{TrustAnchor, TrustAnchorBindError, TrustAnchorError};
+use rpki::data_model::ta::{
+    TaCertificateVerifyError, TrustAnchor, TrustAnchorBindError, TrustAnchorError,
+};
 use rpki::data_model::tal::Tal;
 use url::Url;
 
@@ -76,3 +78,21 @@ fn bind_rejects_resolved_uri_not_listed_in_tal() {
         ))
     ));
 }
+
+#[test]
+fn bind_rejects_tampered_ta_self_signature() {
+    let tal_raw =
+        std::fs::read("tests/fixtures/tal/apnic-rfc7730-https.tal").expect("read TAL fixture");
+    let tal = Tal::decode_bytes(&tal_raw).expect("decode TAL fixture");
+    let mut ta_der = std::fs::read("tests/fixtures/ta/apnic-ta.cer").expect("read TA fixture");
+
+    let last = ta_der.last_mut().expect("TA fixture must not be empty");
+    *last ^= 0x01;
+
+    assert!(matches!(
+        TrustAnchor::bind_der(tal, &ta_der, None),
+        Err(TrustAnchorError::TaSelfSignature(
+            TaCertificateVerifyError::InvalidSelfSignature(_)
+        ))
+    ));
+}