diff --git a/src/gtest/test_keystore.cpp b/src/gtest/test_keystore.cpp
index 7059f2fc8..6b4d08a59 100644
--- a/src/gtest/test_keystore.cpp
+++ b/src/gtest/test_keystore.cpp
@@ -35,10 +35,10 @@ TEST(keystore_tests, StoreAndRetrieveHDSeed) {
     auto seed2 = HDSeed::Random();
     EXPECT_NE(seed, seed2);
 
-    // We should be able to set and retrieve a different seed
-    ASSERT_TRUE(keyStore.SetHDSeed(seed2));
+    // We should not be able to set and retrieve a different seed
+    EXPECT_FALSE(keyStore.SetHDSeed(seed2));
     ASSERT_TRUE(keyStore.GetHDSeed(seedOut));
-    EXPECT_EQ(seed2, seedOut);
+    EXPECT_EQ(seed, seedOut);
 }
 
 TEST(keystore_tests, sapling_keys) {
@@ -276,12 +276,12 @@ TEST(keystore_tests, StoreAndRetrieveHDSeedInEncryptedStore) {
     ASSERT_TRUE(keyStore.GetHDSeed(seedOut));
     EXPECT_EQ(seed, seedOut);
 
-    // 2) Test replacing the seed in an already-encrypted key store
+    // 2) Test replacing the seed in an already-encrypted key store fails
     auto seed2 = HDSeed::Random();
-    ASSERT_TRUE(keyStore.SetHDSeed(seed2));
+    EXPECT_FALSE(keyStore.SetHDSeed(seed2));
     EXPECT_TRUE(keyStore.HaveHDSeed());
     ASSERT_TRUE(keyStore.GetHDSeed(seedOut));
-    EXPECT_EQ(seed2, seedOut);
+    EXPECT_EQ(seed, seedOut);
 
     // 3) Test adding a new seed to an already-encrypted key store
     TestCCryptoKeyStore keyStore2;
diff --git a/src/keystore.cpp b/src/keystore.cpp
index 4fa6c8081..8262c8aab 100644
--- a/src/keystore.cpp
+++ b/src/keystore.cpp
@@ -26,6 +26,11 @@ bool CKeyStore::AddKey(const CKey &key) {
 bool CBasicKeyStore::SetHDSeed(const HDSeed& seed)
 {
     LOCK(cs_SpendingKeyStore);
+    if (!hdSeed.IsNull()) {
+        // Don't allow an existing seed to be changed. We can maybe relax this
+        // restriction later once we have worked out the UX implications.
+        return false;
+    }
     hdSeed = seed;
     return true;
 }
diff --git a/src/wallet/crypter.cpp b/src/wallet/crypter.cpp
index fea563159..88807598a 100644
--- a/src/wallet/crypter.cpp
+++ b/src/wallet/crypter.cpp
@@ -219,7 +219,7 @@ bool CCryptoKeyStore::Unlock(const CKeyingMaterial& vMasterKeyIn)
 
         bool keyPass = false;
         bool keyFail = false;
-        {
+        if (!cryptedHDSeed.first.IsNull()) {
             HDSeed seed;
             if (!DecryptHDSeed(vMasterKeyIn, cryptedHDSeed.second, cryptedHDSeed.first, seed))
             {
@@ -322,6 +322,12 @@ bool CCryptoKeyStore::SetCryptedHDSeed(
             return false;
         }
 
+        if (!cryptedHDSeed.first.IsNull()) {
+            // Don't allow an existing seed to be changed. We can maybe relax this
+            // restriction later once we have worked out the UX implications.
+            return false;
+        }
+
         cryptedHDSeed = std::make_pair(seedFp, vchCryptedSecret);
     }
     return true;
@@ -550,20 +556,22 @@ bool CCryptoKeyStore::EncryptKeys(CKeyingMaterial& vMasterKeyIn)
             return false;
 
         fUseCrypto = true;
-        {
-            std::vector<unsigned char> vchCryptedSecret;
-            // Use seed's fingerprint as IV
-            // TODO: Handle this properly when we make encryption a supported feature
-            auto seedFp = hdSeed.Fingerprint();
-            if (!EncryptSecret(vMasterKeyIn, hdSeed.RawSeed(), seedFp, vchCryptedSecret)) {
-                return false;
-            }
-            // This will call into CWallet to store the crypted seed to disk
-            if (!SetCryptedHDSeed(seedFp, vchCryptedSecret)) {
-                return false;
+        if (!hdSeed.IsNull()) {
+            {
+                std::vector<unsigned char> vchCryptedSecret;
+                // Use seed's fingerprint as IV
+                // TODO: Handle this properly when we make encryption a supported feature
+                auto seedFp = hdSeed.Fingerprint();
+                if (!EncryptSecret(vMasterKeyIn, hdSeed.RawSeed(), seedFp, vchCryptedSecret)) {
+                    return false;
+                }
+                // This will call into CWallet to store the crypted seed to disk
+                if (!SetCryptedHDSeed(seedFp, vchCryptedSecret)) {
+                    return false;
+                }
             }
+            hdSeed = HDSeed();
         }
-        hdSeed = HDSeed();
         BOOST_FOREACH(KeyMap::value_type& mKey, mapKeys)
         {
             const CKey &key = mKey.second;