diff --git a/crypto/asn1/a_type.cc b/crypto/asn1/a_type.cc
index b714340..26d8e26 100644
--- a/crypto/asn1/a_type.cc
+++ b/crypto/asn1/a_type.cc
@@ -346,6 +346,9 @@
   }
 }
 
+static int asn1_marshal_string_with_type(CBB *out, const ASN1_STRING *in,
+                                         int type);
+
 int asn1_marshal_any(CBB *out, const ASN1_TYPE *in) {
   switch (in->type) {
     case V_ASN1_OBJECT:
@@ -374,7 +377,10 @@
     case V_ASN1_SEQUENCE:
     case V_ASN1_SET:
     case V_ASN1_OTHER:
-      return asn1_marshal_any_string(out, in->value.asn1_string);
+      // If |in->type| and the underlying |ASN1_STRING| type don't match, use
+      // |in->type|. See b/446993031.
+      return asn1_marshal_string_with_type(out, in->value.asn1_string,
+                                           in->type);
     default:
       // |ASN1_TYPE|s can have type -1 when default-constructed.
       OPENSSL_PUT_ERROR(ASN1, ASN1_R_WRONG_TYPE);
@@ -382,8 +388,9 @@
   }
 }
 
-int asn1_marshal_any_string(CBB *out, const ASN1_STRING *in) {
-  switch (in->type) {
+static int asn1_marshal_string_with_type(CBB *out, const ASN1_STRING *in,
+                                         int type) {
+  switch (type) {
     case V_ASN1_INTEGER:
     case V_ASN1_NEG_INTEGER:
       return asn1_marshal_integer(out, in, CBS_ASN1_INTEGER);
@@ -420,3 +427,7 @@
       return 0;
   }
 }
+
+int asn1_marshal_any_string(CBB *out, const ASN1_STRING *in) {
+  return asn1_marshal_string_with_type(out, in, in->type);
+}
diff --git a/crypto/asn1/asn1_test.cc b/crypto/asn1/asn1_test.cc
index be865ce..9136c0e 100644
--- a/crypto/asn1/asn1_test.cc
+++ b/crypto/asn1/asn1_test.cc
@@ -2076,6 +2076,47 @@
   EXPECT_EQ(-1, i2d_DIRECTORYSTRING(obj.get(), nullptr));
 }
 
+TEST(ASN1Test, TypeMismatch) {
+  // Pack PSS parameters into an |ASN1_STRING|. This makes an OCTET STRING.
+  bssl::UniquePtr<RSA_PSS_PARAMS> pss(RSA_PSS_PARAMS_new());
+  ASSERT_TRUE(pss);
+  bssl::UniquePtr<ASN1_STRING> str(
+      ASN1_item_pack(pss.get(), ASN1_ITEM_rptr(RSA_PSS_PARAMS), nullptr));
+  ASSERT_TRUE(str);
+  EXPECT_EQ(ASN1_STRING_type(str.get()), V_ASN1_OCTET_STRING);
+
+  // Pass this to |X509_ALGOR_set0| as a |V_ASN1_SEQUENCE|, which uses the
+  // |ASN1_TYPE_set0| calling convention. This leads to an ambiguous state:
+  // whether this should be a SEQUENCE or OCTET STRING value.
+  bssl::UniquePtr<X509_ALGOR> alg(X509_ALGOR_new());
+  ASSERT_TRUE(alg);
+  ASSERT_TRUE(X509_ALGOR_set0(alg.get(), OBJ_nid2obj(NID_rsassaPss),
+                              V_ASN1_SEQUENCE, str.release()));
+
+  // It should be interpreted as a SEQUENCE value and serialize in this way.
+  //
+  // SEQUENCE {
+  //   # rsassa-pss
+  //   OBJECT_IDENTIFIER { 1.2.840.113549.1.1.10 }
+  //   SEQUENCE {}
+  // }
+  //
+  // TODO(davidben): This currently works because |asn1_marshal_any| is careful
+  // to use the |ASN1_TYPE|-level type rather than the |ASN1_STRING|-level type.
+  // Should we also make |ASN1_TYPE_set0| fix the |ASN1_STRING| so fewer
+  // |ASN1_TYPE|s break invariants?
+  static const uint8_t kExpected[] = {0x30, 0x0d, 0x06, 0x09, 0x2a,
+                                      0x86, 0x48, 0x86, 0xf7, 0x0d,
+                                      0x01, 0x01, 0x0a, 0x30, 0x00};
+  TestSerialize(alg.get(), i2d_X509_ALGOR, kExpected);
+
+  // Even if |X509_ALGOR_set0| is fixed to maintain invariants, enough types are
+  // publicly exposed that we should make sure we handle the invalid state. This
+  // test is currently a no-op, but will not be if the above TODO is resolved.
+  alg->parameter->value.asn1_string->type = V_ASN1_OCTET_STRING;
+  TestSerialize(alg.get(), i2d_X509_ALGOR, kExpected);
+}
+
 TEST(ASN1Test, StringTableSorted) {
   const ASN1_STRING_TABLE *table;
   size_t table_len;
@@ -2130,6 +2171,7 @@
   bssl::UniquePtr<ASN1_STRING> str(
       ASN1_item_pack(val.get(), ASN1_ITEM_rptr(BASIC_CONSTRAINTS), nullptr));
   ASSERT_TRUE(str);
+  EXPECT_EQ(ASN1_STRING_type(str.get()), V_ASN1_OCTET_STRING);
   EXPECT_EQ(
       Bytes(ASN1_STRING_get0_data(str.get()), ASN1_STRING_length(str.get())),
       Bytes(kExpected));
@@ -2138,6 +2180,7 @@
   str.reset(ASN1_item_pack(val.get(), ASN1_ITEM_rptr(BASIC_CONSTRAINTS), &raw));
   ASSERT_TRUE(str);
   EXPECT_EQ(raw, str.get());
+  EXPECT_EQ(ASN1_STRING_type(str.get()), V_ASN1_OCTET_STRING);
   EXPECT_EQ(
       Bytes(ASN1_STRING_get0_data(str.get()), ASN1_STRING_length(str.get())),
       Bytes(kExpected));
@@ -2148,6 +2191,7 @@
   EXPECT_TRUE(
       ASN1_item_pack(val.get(), ASN1_ITEM_rptr(BASIC_CONSTRAINTS), &raw));
   EXPECT_EQ(raw, str.get());
+  EXPECT_EQ(ASN1_STRING_type(str.get()), V_ASN1_OCTET_STRING);
   EXPECT_EQ(
       Bytes(ASN1_STRING_get0_data(str.get()), ASN1_STRING_length(str.get())),
       Bytes(kExpected));