diff --git a/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt b/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt
index d7d3e8f205..75bdb2e73b 100644
--- a/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt
+++ b/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt
@@ -4,6 +4,7 @@ import net.corda.core.crypto.CompositeKey.NodeAndWeight
 import net.corda.core.serialization.CordaSerializable
 import org.bouncycastle.asn1.*
 import org.bouncycastle.asn1.x509.SubjectPublicKeyInfo
+import java.nio.ByteBuffer
 import java.security.PublicKey
 import java.util.*
 
@@ -109,11 +110,11 @@ class CompositeKey private constructor (val threshold: Int,
             // We don't allow zero or negative weights. Minimum weight = 1.
             require (weight > 0) { "A non-positive weight was detected. Node info: $this"  }
         }
+
         override fun compareTo(other: NodeAndWeight): Int {
-            if (weight == other.weight) {
-                return node.hashCode().compareTo(other.node.hashCode())
-            }
-            else return weight.compareTo(other.weight)
+            return if (weight == other.weight) {
+                ByteBuffer.wrap(node.toSHA256Bytes()).compareTo(ByteBuffer.wrap(other.node.toSHA256Bytes()))
+            } else weight.compareTo(other.weight)
         }
 
         override fun toASN1Primitive(): ASN1Primitive {
diff --git a/core/src/main/kotlin/net/corda/core/crypto/EncodingUtils.kt b/core/src/main/kotlin/net/corda/core/crypto/EncodingUtils.kt
index b1681a19f9..a79821b760 100644
--- a/core/src/main/kotlin/net/corda/core/crypto/EncodingUtils.kt
+++ b/core/src/main/kotlin/net/corda/core/crypto/EncodingUtils.kt
@@ -65,4 +65,4 @@ fun String.hexToBase64(): String = hexToByteArray().toBase64()
 //       structure, e.g. mapping a PublicKey to a condition with the specific feature (ED25519).
 fun parsePublicKeyBase58(base58String: String): PublicKey = base58String.base58ToByteArray().deserialize<PublicKey>()
 fun PublicKey.toBase58String(): String = this.serialize().bytes.toBase58()
-fun PublicKey.toSHA256Bytes(): ByteArray = this.serialize().bytes.sha256().bytes
+fun PublicKey.toSHA256Bytes(): ByteArray = this.serialize().bytes.sha256().bytes // TODO: decide on the format of hashed key (encoded Vs serialised).
diff --git a/core/src/test/kotlin/net/corda/core/crypto/CompositeKeyTests.kt b/core/src/test/kotlin/net/corda/core/crypto/CompositeKeyTests.kt
index 591d56001a..bee35e0a9d 100644
--- a/core/src/test/kotlin/net/corda/core/crypto/CompositeKeyTests.kt
+++ b/core/src/test/kotlin/net/corda/core/crypto/CompositeKeyTests.kt
@@ -1,7 +1,7 @@
 package net.corda.core.crypto
 
-import net.corda.core.utilities.OpaqueBytes
 import net.corda.core.serialization.serialize
+import net.corda.core.utilities.OpaqueBytes
 import org.junit.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertFailsWith
@@ -259,4 +259,22 @@ class CompositeKeyTests {
         val signaturesWithoutRSA = listOf(K1Signature, R1Signature, EdSignature, SPSignature)
         assertFalse { compositeKey.isFulfilledBy(signaturesWithoutRSA.byKeys()) }
     }
+
+    @Test
+    fun `CompositeKey deterministic children sorting`() {
+        val (_, pub1) = Crypto.generateKeyPair(Crypto.EDDSA_ED25519_SHA512)
+        val (_, pub2) = Crypto.generateKeyPair(Crypto.ECDSA_SECP256K1_SHA256)
+        val (_, pub3) = Crypto.generateKeyPair(Crypto.RSA_SHA256)
+        val (_, pub4) = Crypto.generateKeyPair(Crypto.EDDSA_ED25519_SHA512)
+        val (_, pub5) = Crypto.generateKeyPair(Crypto.ECDSA_SECP256R1_SHA256)
+        val (_, pub6) = Crypto.generateKeyPair(Crypto.SPHINCS256_SHA256)
+        val (_, pub7) = Crypto.generateKeyPair(Crypto.ECDSA_SECP256K1_SHA256)
+
+        // Using default weight = 1, thus all weights are equal.
+        val composite1 = CompositeKey.Builder().addKeys(pub1, pub2, pub3, pub4, pub5, pub6, pub7).build() as CompositeKey
+        // Store in reverse order.
+        val composite2 = CompositeKey.Builder().addKeys(pub7, pub6, pub5, pub4, pub3, pub2, pub1).build() as CompositeKey
+        // There are 7! = 5040 permutations, but as sorting is deterministic the following should never fail.
+        assertEquals(composite1.children, composite2.children)
+    }
 }