diff --git a/include/zone.h b/include/zone.h
index bb564eb..0d5e84f 100644
--- a/include/zone.h
+++ b/include/zone.h
@@ -221,8 +221,10 @@ extern "C" {
 #define ZONE_SVC_PARAM_KEY_IPV6HINT (6u)
 /** URI template in relative form @rfc{9461} */
 #define ZONE_SVC_PARAM_KEY_DOHPATH (7u)
-/** Target is an Oblivious HTTP service @draft{ohai,svcb-config} */
+/** Target is an Oblivious HTTP service @rfc{9540} */
 #define ZONE_SVC_PARAM_KEY_OHTTP (8u)
+/** Supported groups in TLS @draft{ietf, tls-key-share-prediction} */
+#define ZONE_SVC_PARAM_KEY_TLS_SUPPORTED_GROUPS (9u)
 /** Reserved ("invalid key") @rfc{9460} */
 #define ZONE_SVC_PARAM_KEY_INVALID_KEY (65535u)
 /** @} */
diff --git a/src/generic/parser.h b/src/generic/parser.h
index f1823de..323f4aa 100644
--- a/src/generic/parser.h
+++ b/src/generic/parser.h
@@ -49,7 +49,7 @@ struct string {
 typedef struct mnemonic mnemonic_t;
 struct mnemonic {
   struct {
-    char data[16];
+    char data[16]; /* MUST be 16 because of usage with SIMD cmpeq */
     size_t length;
   } key;
   uint32_t value;
@@ -78,7 +78,13 @@ typedef int32_t (*parse_svc_param_t)(
   const token_t *);
 
 struct svc_param_info {
-  mnemonic_t name;
+  struct {
+    struct {
+      char data[24];
+      size_t length;
+    } key;
+    uint32_t value;
+  } name;
   uint32_t has_value;
   parse_svc_param_t parse, parse_lax;
 };
diff --git a/src/generic/svcb.h b/src/generic/svcb.h
index 0011bef..ec40aee 100644
--- a/src/generic/svcb.h
+++ b/src/generic/svcb.h
@@ -366,6 +366,55 @@ static int32_t parse_unknown(
   return 0;
 }
 
+nonnull_all
+static int32_t parse_tls_supported_groups(
+  parser_t *parser,
+  const type_info_t *type,
+  const rdata_info_t *field,
+  uint16_t key,
+  const svc_param_info_t *param,
+  rdata_t *rdata,
+  const token_t *token)
+{
+  const char *t = token->data, *te = token->data + token->length;
+  const uint8_t *rdata_start = rdata->octets;
+
+  (void)field;
+  (void)key;
+  (void)param;
+
+  while (t < te && rdata->octets+2 <= rdata->limit) {
+    uint64_t number = 0;
+    for (;; t++) {
+      const uint64_t digit = (uint8_t)*t - '0';
+      if (digit > 9)
+        break;
+      number = number * 10 + digit;
+    }
+
+    uint16_t group = (uint16_t)number;
+    group = htobe16(group);
+    memcpy(rdata->octets, &group, 2);
+    rdata->octets += 2;
+    if (number > 65535)
+      SYNTAX_ERROR(parser, "Invalid tls-supported-group in %s", NAME(type));
+
+    const uint8_t *g;
+    for (g = rdata_start; g < rdata->octets - 2; g += 2) {
+      if (memcmp(g, &group, 2) == 0)
+        SEMANTIC_ERROR(parser, "Duplicate group in tls-supported-groups in %s", NAME(type));
+    }
+    if (*t != ',')
+      break;
+    else
+      t++;
+  }
+
+  if (t != te || rdata->octets > rdata->limit)
+    SYNTAX_ERROR(parser, "Invalid tls-supported-groups in %s", NAME(type));
+  return 0;
+}
+
 nonnull_all
 static int32_t parse_mandatory_lax(
   parser_t *parser,
@@ -421,7 +470,13 @@ static const svc_param_info_t svc_params[] = {
   //   If the "alpn" SvcParam indicates support for HTTP, "dohpath" MUST be
   //   present.
   SVC_PARAM("dohpath", 7u, MANDATORY_VALUE, parse_dohpath, parse_dohpath),
-  SVC_PARAM("ohttp", 8u, 0u, 0, 0),
+  // RFC9540 section 4.
+  //   Both the presentation and wire-format values for the "ohttp" parameter
+  //   MUST be empty.
+  SVC_PARAM("ohttp", 8u, NO_VALUE, parse_unknown, parse_unknown),
+  // draft-ietf-tls-key-share-prediction-01 section 3.1
+  SVC_PARAM("tls-supported-groups", 9u, MANDATORY_VALUE,
+            parse_tls_supported_groups, parse_tls_supported_groups),
 };
 
 static const svc_param_info_t unknown_svc_param =
@@ -485,6 +540,8 @@ static really_inline size_t scan_svc_param(
     return (void)(*param = &svc_params[(*key = ZONE_SVC_PARAM_KEY_DOHPATH)]), 7;
   else if (memcmp(data, "ohttp", 5) == 0)
     return (void)(*param = &svc_params[(*key = ZONE_SVC_PARAM_KEY_OHTTP)]), 5;
+  else if (memcmp(data, "tls-supported-groups", 20) == 0)
+    return (void)(*param = &svc_params[(*key = ZONE_SVC_PARAM_KEY_TLS_SUPPORTED_GROUPS)]), 20;
   else if (memcmp(data, "key", 3) == 0)
     return scan_unknown_svc_param_key(data, key, param);
   else
diff --git a/tests/svcb.c b/tests/svcb.c
index f00e575..21b7dcd 100644
--- a/tests/svcb.c
+++ b/tests/svcb.c
@@ -690,6 +690,80 @@ static const rdata_t nsd_s09_rdata =
     0x00, 0x01, 0x00, 0x03, 2, 'h', '2',
     0x00, 0x07, 0x00, 0x12, '/', 'd', 'n', 's', '-', 'q', 'u', 'e', 'r', 'y', '{', 0xc3, 0xa9, '?', 'd', 'n', 's', '}');
 
+// From RFC9540 Section 4.1
+static const char ohttp_s1_text[] =
+  PAD("ohttp-s1 HTTPS 1 . ( alpn=h2 ohttp )");
+static const rdata_t ohttp_s1_rdata =
+  RDATA(
+    0x00, 0x01, // priority
+    0x00, // target
+    0x00, 0x01, 0x00, 0x03, 2, 'h', '2', // alpn=h2
+    0x00, 0x08, 0x00, 0x00 // ohttp
+    );
+
+static const char ohttp_s2_text[] =
+  PAD("ohttp-s2 HTTPS 1 . ( mandatory=ohttp ohttp )");
+static const rdata_t ohttp_s2_rdata =
+  RDATA(
+    0x00, 0x01, // priority
+    0x00, // target
+    0x00, 0x00, 0x00, 0x02, 0x00, 0x08, // mandatory=ohttp
+    0x00, 0x08, 0x00, 0x00 // ohttp
+    );
+
+// From RFC9540 Section 4.2.1
+static const char ohttp_s3_text[] =
+  PAD("ohttp-s3  SVCB  1 doh.example.net. ( alpn=h2 dohpath=/dns-query{?dns} ohttp )");
+static const rdata_t ohttp_s3_rdata =
+  RDATA(
+    0x00, 0x01, // priority
+    3, 'd', 'o', 'h', 7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 3, 'n', 'e', 't', 0, // target
+    0x00, 0x01, 0x00, 0x03, 2, 'h', '2', // alpn=h2
+    0x00, 0x07, 0x00, 0x10, '/', 'd', 'n', 's', '-', 'q', 'u', 'e', 'r', 'y', '{', '?', 'd', 'n', 's', '}',
+    0x00, 0x08, 0x00, 0x00 // ohttp
+    );
+
+// From RFC9540 Section 4:
+//   Both the presentation and wire-format values for the "ohttp" parameter
+//   MUST be empty.
+static const char ohttp_f1_text[] =
+  PAD("ohttp-f1 HTTPS 1 . ( alpn=h2 ohttp=hopsa )");
+
+#if 0
+// wire-format non-empty value for the "ohttp" parameter does not fail yet
+static const char ohttp_f2_generic_text[] =
+  PAD("ohttp-f2 SVCB \\# 19 (\n"
+      "00 01                      ; priority\n"
+      "00                         ; target\n"
+      "00 01 00 03 02 68 32       ; alpn=h2\n"
+      "00 08 00 05 68 6f 70 73 61 ; ohttp=hopsa\n"
+      ")");
+#endif
+
+// From draft-ietf-tls-key-share-prediction-01 Section 3.1
+static const char tsg_s1_text[] =
+  PAD("tsg-s1 7200  IN SVCB 3 server.example.net. (\n"
+      "port=\"8004\" tls-supported-groups=29,23 )");
+static const rdata_t tsg_s1_rdata =
+  RDATA(
+    0x00, 0x03, // priority
+    6, 's', 'e', 'r', 'v', 'e', 'r', 7, 'e', 'x', 'a', 'm', 'p', 'l', 'e', 3, 'n', 'e', 't', 0, // target
+    0x00, 0x03, 0x00, 0x02, 0x1f, 0x44, // port="8004"
+    0x00, 0x09, 0x00, 0x04, 0x00, 0x1d, 0x00, 0x17 // tls-supported-groups=29,23
+    );
+
+// From draft-ietf-tls-key-share-prediction-01 Section 3.1:
+//   An empty list of values is invalid
+static const char tsg_f1_text[] =
+  PAD("tsg-f1 7200  IN SVCB 3 server.example.net. (\n"
+      "port=\"8004\" tls-supported-groups )");
+
+// From draft-ietf-tls-key-share-prediction-01 Section 3.1:
+//   An list containing duplicates is invalid
+static const char tsg_f2_text[] =
+  PAD("tsg-f2 7200  IN SVCB 3 server.example.net. (\n"
+      "port=\"8004\" tls-supported-groups=29,23,29 )");
+
 // FIXME: make a test that verifies correct behavior for no-default-alpn="some value"
 
 typedef struct test test_t;
@@ -777,7 +851,14 @@ static const test_t tests[] = {
   { true, ZONE_TYPE_HTTPS, 0, nsd_s05_https_text, &nsd_s05_https_secondary_rdata },
   { false, ZONE_TYPE_HTTPS, 0, nsd_s06_text, &nsd_s06_rdata },
   { false, ZONE_TYPE_HTTPS, 0, nsd_s08_text, &nsd_s08_rdata },
-  { false, ZONE_TYPE_HTTPS, 0, nsd_s09_text, &nsd_s09_rdata }
+  { false, ZONE_TYPE_HTTPS, 0, nsd_s09_text, &nsd_s09_rdata },
+  { false, ZONE_TYPE_HTTPS, 0, ohttp_s1_text, &ohttp_s1_rdata },
+  { false, ZONE_TYPE_HTTPS, 0, ohttp_s2_text, &ohttp_s2_rdata },
+  { false, ZONE_TYPE_SVCB, 0, ohttp_s3_text, &ohttp_s3_rdata },
+  { false, ZONE_TYPE_HTTPS, ZONE_SEMANTIC_ERROR, ohttp_f1_text, NULL },
+  { false, ZONE_TYPE_SVCB, 0, tsg_s1_text, &tsg_s1_rdata },
+  { false, ZONE_TYPE_SVCB, ZONE_SEMANTIC_ERROR, tsg_f1_text, NULL },
+  { false, ZONE_TYPE_SVCB, ZONE_SEMANTIC_ERROR, tsg_f2_text, NULL }
 };
 
 static int32_t add_rr(