diff --git a/core/src/main/kotlin/net/corda/core/crypto/composite/CompositeKey.kt b/core/src/main/kotlin/net/corda/core/crypto/composite/CompositeKey.kt
index 4410171307..a1e31e2f01 100644
--- a/core/src/main/kotlin/net/corda/core/crypto/composite/CompositeKey.kt
+++ b/core/src/main/kotlin/net/corda/core/crypto/composite/CompositeKey.kt
@@ -262,7 +262,9 @@ class CompositeKey private constructor(val threshold: Int, children: List<NodeAn
             else if (n == 1) {
                 require(threshold == null || threshold == children.first().weight)
                 { "Trying to build invalid CompositeKey, threshold value different than weight of single child node." }
-                children.first().node // We can assume that this node is a correct CompositeKey.
+                // Returning the only child node which is [PublicKey] itself. We need to avoid single-key [CompositeKey] instances,
+                // as there are scenarios where developers expected the underlying key and its composite versions to be equivalent.
+                children.first().node
             } else throw IllegalArgumentException("Trying to build CompositeKey without child nodes.")
         }
     }
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 b34d2cc976..62169f8c21 100644
--- a/core/src/test/kotlin/net/corda/core/crypto/CompositeKeyTests.kt
+++ b/core/src/test/kotlin/net/corda/core/crypto/CompositeKeyTests.kt
@@ -25,16 +25,16 @@ class CompositeKeyTests : TestDependencyInjectionBase() {
     @JvmField
     val tempFolder: TemporaryFolder = TemporaryFolder()
 
-    val aliceKey = generateKeyPair()
-    val bobKey = generateKeyPair()
-    val charlieKey = generateKeyPair()
+    private val aliceKey = generateKeyPair()
+    private val bobKey = generateKeyPair()
+    private val charlieKey = generateKeyPair()
 
-    val alicePublicKey: PublicKey = aliceKey.public
-    val bobPublicKey: PublicKey = bobKey.public
-    val charliePublicKey: PublicKey = charlieKey.public
+    private val alicePublicKey: PublicKey = aliceKey.public
+    private val bobPublicKey: PublicKey = bobKey.public
+    private val charliePublicKey: PublicKey = charlieKey.public
 
-    val message = OpaqueBytes("Transaction".toByteArray())
-    val secureHash = message.sha256()
+    private val message = OpaqueBytes("Transaction".toByteArray())
+    private val secureHash = message.sha256()
 
     // By lazy is required so that the serialisers are configured before vals initialisation takes place (they internally invoke serialise).
     val aliceSignature by lazy { aliceKey.sign(SignableData(secureHash, SignatureMetadata(1, Crypto.findSignatureScheme(alicePublicKey).schemeNumberID))) }
@@ -43,7 +43,6 @@ class CompositeKeyTests : TestDependencyInjectionBase() {
 
     @Test
     fun `(Alice) fulfilled by Alice signature`() {
-        println(aliceKey.serialize().hash)
         assertTrue { alicePublicKey.isFulfilledBy(aliceSignature.by) }
         assertFalse { alicePublicKey.isFulfilledBy(charlieSignature.by) }
     }