diff --git a/docs/driver-only-builds.md b/docs/driver-only-builds.md
index 4095d8e..5d950b0 100644
--- a/docs/driver-only-builds.md
+++ b/docs/driver-only-builds.md
@@ -277,6 +277,11 @@
 `[PSA_WANT|MBEDTLS_PSA_ACCEL]_ALG_FFDH` allow builds accelerating FFDH and
 removing builtin support (i.e. `MBEDTLS_DHM_C`).
 
+Note that the PSA API only supports FFDH with RFC 7919 groups, whereas the
+Mbed TLS legacy API supports custom groups. As a consequence, the TLS layer
+of Mbed TLS only supports DHE cipher suites if built-in FFDH
+(`MBEDTLS_DHM_C`) is present, even when `MBEDTLS_USE_PSA_CRYPTO` is enabled.
+
 RSA
 ---
 
diff --git a/tests/scripts/analyze_outcomes.py b/tests/scripts/analyze_outcomes.py
index 5b4deb6..5193a3b 100755
--- a/tests/scripts/analyze_outcomes.py
+++ b/tests/scripts/analyze_outcomes.py
@@ -468,6 +468,12 @@
                 'bignum.generated', 'bignum.misc',
             ],
             'ignored_tests': {
+                'ssl-opt': [
+                    # DHE support in TLS 1.2 requires built-in MBEDTLS_DHM_C
+                    # (because it needs custom groups, which PSA does not
+                    # provide), even with MBEDTLS_USE_PSA_CRYPTO.
+                    re.compile(r'PSK callback:.*\bdhe-psk\b.*'),
+                ],
                 'test_suite_platform': [
                     # Incompatible with sanitizers (e.g. ASan). If the driver
                     # component uses a sanitizer but the reference component