diff --git a/crypto/curve25519/ed25519_test.cc b/crypto/curve25519/ed25519_test.cc
index 4f34675..d56abe6 100644
--- a/crypto/curve25519/ed25519_test.cc
+++ b/crypto/curve25519/ed25519_test.cc
@@ -64,6 +64,48 @@
   };
 
   EXPECT_FALSE(ED25519_verify(kMsg, sizeof(kMsg), kSig, kPub));
+
+  // The following inputs try to exercise the boundaries of the order check,
+  // where s is near the order above and below. EdDSA hashes the public key with
+  // the message, which frustrates constructing actual boundary cases. Instead,
+  // these inputs were found by randomly generating signatures. kSigValid had
+  // the highest s value. kSigInvalid had the lowest s value, and then the order
+  // was added.
+  //
+  // This isn't ideal, but it is sensitive to the most significant 32 bits.
+  //
+  // The private key seed for kPub2 is
+  // a59a4130fcfd293c9737db8f14177ce034305cf34bdc4346f24b4d262e07b5c2.
+  static const uint8_t kPub2[] = {
+      0x10, 0x0f, 0xdf, 0x47, 0xfb, 0x94, 0xf1, 0x53, 0x6a, 0x4f, 0x7c,
+      0x3f, 0xda, 0x27, 0x38, 0x3f, 0xa0, 0x33, 0x75, 0xa8, 0xf5, 0x27,
+      0xc5, 0x37, 0xe6, 0xf1, 0x70, 0x3c, 0x47, 0xf9, 0x4f, 0x86};
+  static const uint8_t kMsgValid[] = {
+      0x12, 0x4e, 0x58, 0x3f, 0x8b, 0x8e, 0xca, 0x58, 0xbb, 0x29, 0xc2,
+      0x71, 0xb4, 0x1d, 0x36, 0x98, 0x6b, 0xbc, 0x45, 0x54, 0x1f, 0x8e,
+      0x51, 0xf9, 0xcb, 0x01, 0x33, 0xec, 0xa4, 0x47, 0x60, 0x1e};
+  static const uint8_t kSigValid[] = {
+      0xda, 0xc1, 0x19, 0xd6, 0xca, 0x87, 0xfc, 0x59, 0xae, 0x61, 0x1c,
+      0x15, 0x70, 0x48, 0xf4, 0xd4, 0xfc, 0x93, 0x2a, 0x14, 0x9d, 0xbe,
+      0x20, 0xec, 0x6e, 0xff, 0xd1, 0x43, 0x6a, 0xbf, 0x83, 0xea, 0x05,
+      0xc7, 0xdf, 0x0f, 0xef, 0x06, 0x14, 0x72, 0x41, 0x25, 0x91, 0x13,
+      0x90, 0x9b, 0xc7, 0x1b, 0xd3, 0xc5, 0x3b, 0xa4, 0x46, 0x4f, 0xfc,
+      0xad, 0x3c, 0x09, 0x68, 0xf2, 0xff, 0xff, 0xff, 0x0f};
+  static const uint8_t kMsgInvalid[] = {
+      0x6a, 0x0b, 0xc2, 0xb0, 0x05, 0x7c, 0xed, 0xfc, 0x0f, 0xa2, 0xe3,
+      0xf7, 0xf7, 0xd3, 0x92, 0x79, 0xb3, 0x0f, 0x45, 0x4a, 0x69, 0xdf,
+      0xd1, 0x11, 0x7c, 0x75, 0x8d, 0x86, 0xb1, 0x9d, 0x85, 0xe0};
+  static const uint8_t kSigInvalid[] = {
+      0x09, 0x71, 0xf8, 0x6d, 0x2c, 0x9c, 0x78, 0x58, 0x25, 0x24, 0xa1,
+      0x03, 0xcb, 0x9c, 0xf9, 0x49, 0x52, 0x2a, 0xe5, 0x28, 0xf8, 0x05,
+      0x4d, 0xc2, 0x01, 0x07, 0xd9, 0x99, 0xbe, 0x67, 0x3f, 0xf4, 0xe2,
+      0x5e, 0xbf, 0x2f, 0x29, 0x28, 0x76, 0x6b, 0x12, 0x48, 0xbe, 0xc6,
+      0xe9, 0x16, 0x97, 0x77, 0x5f, 0x84, 0x46, 0x63, 0x9e, 0xde, 0x46,
+      0xad, 0x4d, 0xf4, 0x05, 0x30, 0x00, 0x00, 0x00, 0x10};
+
+  EXPECT_TRUE(ED25519_verify(kMsgValid, sizeof(kMsgValid), kSigValid, kPub2));
+  EXPECT_FALSE(
+      ED25519_verify(kMsgInvalid, sizeof(kMsgInvalid), kSigInvalid, kPub2));
 }
 
 TEST(Ed25519Test, KeypairFromSeed) {