diff --git a/.ci/api-current.txt b/.ci/api-current.txt
index 8fd222b418..209a163a1e 100644
--- a/.ci/api-current.txt
+++ b/.ci/api-current.txt
@@ -6454,7 +6454,7 @@ public final class net.corda.testing.node.MockServicesKt extends java.lang.Objec
   @NotNull
   public static final T createMockCordaService(net.corda.testing.node.MockServices, kotlin.jvm.functions.Function1<? super net.corda.core.node.AppServiceHub, ? extends T>)
   @NotNull
-  public static final net.corda.node.services.identity.InMemoryIdentityService makeTestIdentityService(net.corda.core.identity.PartyAndCertificate...)
+  public static final net.corda.core.node.services.IdentityService makeTestIdentityService(net.corda.core.identity.PartyAndCertificate...)
 ##
 public final class net.corda.testing.node.NodeTestUtils extends java.lang.Object
   @NotNull
diff --git a/testing/node-driver/src/main/kotlin/net/corda/testing/node/MockServices.kt b/testing/node-driver/src/main/kotlin/net/corda/testing/node/MockServices.kt
index 6336713ed7..9ff700eb08 100644
--- a/testing/node-driver/src/main/kotlin/net/corda/testing/node/MockServices.kt
+++ b/testing/node-driver/src/main/kotlin/net/corda/testing/node/MockServices.kt
@@ -47,10 +47,10 @@ import java.util.*
 import java.util.function.Consumer
 import javax.persistence.EntityManager
 
-/**
- * Returns a simple [InMemoryIdentityService] containing the supplied [identities].
- */
-fun makeTestIdentityService(vararg identities: PartyAndCertificate) = InMemoryIdentityService(identities.toList(), DEV_ROOT_CA.certificate)
+/** Returns a simple [IdentityService] containing the supplied [identities]. */
+fun makeTestIdentityService(vararg identities: PartyAndCertificate): IdentityService {
+    return InMemoryIdentityService(identities.toList(), DEV_ROOT_CA.certificate)
+}
 
 /**
  * An implementation of [ServiceHub] that is designed for in-memory unit tests of contract validation logic. It has