diff --git a/contracts/src/main/kotlin/com/r3corda/contracts/testing/WalletFiller.kt b/contracts/src/main/kotlin/com/r3corda/contracts/testing/WalletFiller.kt
index 2a9bd90fac..456b8dd391 100644
--- a/contracts/src/main/kotlin/com/r3corda/contracts/testing/WalletFiller.kt
+++ b/contracts/src/main/kotlin/com/r3corda/contracts/testing/WalletFiller.kt
@@ -66,6 +66,7 @@ private fun calculateRandomlySizedAmounts(howMuch: Amount<Currency>, min: Int, m
     val numStates = min + Math.floor(rng.nextDouble() * (max - min)).toInt()
     val amounts = LongArray(numStates)
     val baseSize = howMuch.quantity / numStates
+    check(baseSize > 0) { baseSize }
     var filledSoFar = 0L
     for (i in 0..numStates - 1) {
         if (i < numStates - 1) {
@@ -76,6 +77,7 @@ private fun calculateRandomlySizedAmounts(howMuch: Amount<Currency>, min: Int, m
             // Handle inexact rounding.
             amounts[i] = howMuch.quantity - filledSoFar
         }
+        check(amounts[i] >= 0) { amounts[i] }
     }
     check(amounts.sum() == howMuch.quantity)
     return amounts
diff --git a/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt b/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt
index 0f81331f5f..11022a2086 100644
--- a/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt
+++ b/core/src/main/kotlin/com/r3corda/core/crypto/CryptoUtilities.kt
@@ -5,9 +5,9 @@ import com.r3corda.core.serialization.OpaqueBytes
 import com.r3corda.core.serialization.SerializedBytes
 import com.r3corda.core.serialization.deserialize
 import net.i2p.crypto.eddsa.EdDSAEngine
+import net.i2p.crypto.eddsa.EdDSAPublicKey
 import java.math.BigInteger
 import java.security.*
-import java.security.interfaces.ECPublicKey
 import net.i2p.crypto.eddsa.KeyPairGenerator as EddsaKeyPairGenerator
 
 fun newSecureRandom(): SecureRandom {
@@ -158,8 +158,8 @@ fun PublicKey.verifyWithECDSA(content: ByteArray, signature: DigitalSignature) {
 
 /** Render a public key to a string, using a short form if it's an elliptic curve public key */
 fun PublicKey.toStringShort(): String {
-    return (this as? ECPublicKey)?.let { key ->
-        "DL" + Base58.encode(key.w.affineX.toByteArray())   // DL -> Distributed Ledger
+    return (this as? EdDSAPublicKey)?.let { key ->
+        "DL" + Base58.encode(key.abyte)   // DL -> Distributed Ledger
     } ?: toString()
 }
 
diff --git a/node/src/main/kotlin/com/r3corda/node/internal/testing/MockNode.kt b/node/src/main/kotlin/com/r3corda/node/internal/testing/MockNode.kt
index ea7e7fb279..6245192984 100644
--- a/node/src/main/kotlin/com/r3corda/node/internal/testing/MockNode.kt
+++ b/node/src/main/kotlin/com/r3corda/node/internal/testing/MockNode.kt
@@ -121,7 +121,11 @@ class MockNetwork(private val networkSendManuallyPumped: Boolean = false,
             override val nearestCity: String = "Atlantis"
         }
         val node = nodeFactory.create(path, config, this, networkMapAddress, advertisedServices.toSet(), id, keyPair)
-        if (start) node.setup().start()
+        if (start) {
+            node.setup().start()
+            if (threadPerNode && networkMapAddress != null)
+                node.networkMapRegistrationFuture.get()   // Block and wait for the node to register in the net map.
+        }
         _nodes.add(node)
         return node
     }