diff --git a/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminModifyPeer.java b/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminModifyPeer.java
index 3649bac7ee..bae4884425 100644
--- a/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminModifyPeer.java
+++ b/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminModifyPeer.java
@@ -20,7 +20,6 @@ import tech.pegasys.pantheon.ethereum.jsonrpc.internal.response.JsonRpcErrorResp
 import tech.pegasys.pantheon.ethereum.jsonrpc.internal.response.JsonRpcResponse;
 import tech.pegasys.pantheon.ethereum.p2p.P2pDisabledException;
 import tech.pegasys.pantheon.ethereum.p2p.api.P2PNetwork;
-import tech.pegasys.pantheon.util.enode.EnodeURL;
 
 public abstract class AdminModifyPeer implements JsonRpcMethod {
 
@@ -43,7 +42,9 @@ public abstract class AdminModifyPeer implements JsonRpcMethod {
     } catch (final InvalidJsonRpcParameters e) {
       return new JsonRpcErrorResponse(req.getId(), JsonRpcError.INVALID_PARAMS);
     } catch (final IllegalArgumentException e) {
-      if (e.getMessage().contains(EnodeURL.INVALID_NODE_ID_LENGTH)) {
+      if (e.getMessage()
+          .endsWith(
+              "Invalid node ID: node ID must have exactly 128 hexadecimal characters and should not include any '0x' hex prefix.")) {
         return new JsonRpcErrorResponse(req.getId(), JsonRpcError.ENODE_ID_INVALID);
       } else {
         return new JsonRpcErrorResponse(req.getId(), JsonRpcError.PARSE_ERROR);
diff --git a/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/response/JsonRpcError.java b/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/response/JsonRpcError.java
index e64745412f..e99b406757 100644
--- a/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/response/JsonRpcError.java
+++ b/ethereum/jsonrpc/src/main/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/response/JsonRpcError.java
@@ -12,8 +12,6 @@
  */
 package tech.pegasys.pantheon.ethereum.jsonrpc.internal.response;
 
-import tech.pegasys.pantheon.util.enode.EnodeURL;
-
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonFormat;
 import com.fasterxml.jackson.annotation.JsonGetter;
@@ -101,7 +99,9 @@ public enum JsonRpcError {
   CANT_CONNECT_TO_LOCAL_PEER(-32100, "Cannot add local node as peer."),
 
   // Invalid input errors
-  ENODE_ID_INVALID(-32000, EnodeURL.INVALID_NODE_ID_LENGTH);
+  ENODE_ID_INVALID(
+      -32000,
+      "Invalid node ID: node ID must have exactly 128 hexadecimal characters and should not include any '0x' hex prefix.");
 
   private final int code;
   private final String message;
diff --git a/ethereum/jsonrpc/src/test/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminAddPeerTest.java b/ethereum/jsonrpc/src/test/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminAddPeerTest.java
index 79dac1b961..85ead9586e 100644
--- a/ethereum/jsonrpc/src/test/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminAddPeerTest.java
+++ b/ethereum/jsonrpc/src/test/java/tech/pegasys/pantheon/ethereum/jsonrpc/internal/methods/AdminAddPeerTest.java
@@ -100,6 +100,25 @@ public class AdminAddPeerTest {
     assertThat(actualResponse).isEqualToComparingFieldByField(expectedResponse);
   }
 
+  @Test
+  public void requestHasInvalidEnodeLength() {
+    String invalidLengthEnode =
+        "enode://"
+            + "0000000000000000000000000000000"
+            + "00000000000000000000000000000000"
+            + "00000000000000000000000000000000"
+            + "00000000000000000000000000000000"
+            + "@127.0.0.1:30303";
+    final JsonRpcRequest request =
+        new JsonRpcRequest("2.0", "admin_addPeer", new String[] {invalidLengthEnode});
+    final JsonRpcResponse expectedResponse =
+        new JsonRpcErrorResponse(request.getId(), JsonRpcError.ENODE_ID_INVALID);
+
+    final JsonRpcResponse actualResponse = method.response(request);
+
+    assertThat(actualResponse).isEqualToComparingFieldByField(expectedResponse);
+  }
+
   @Test
   public void requestAddsValidEnode() {
     when(p2pNetwork.addMaintainConnectionPeer(any())).thenReturn(true);
diff --git a/util/src/main/java/tech/pegasys/pantheon/util/enode/EnodeURL.java b/util/src/main/java/tech/pegasys/pantheon/util/enode/EnodeURL.java
index 8461611dc5..f1b55898f5 100644
--- a/util/src/main/java/tech/pegasys/pantheon/util/enode/EnodeURL.java
+++ b/util/src/main/java/tech/pegasys/pantheon/util/enode/EnodeURL.java
@@ -41,10 +41,6 @@ public class EnodeURL {
   private final OptionalInt listeningPort;
   private final OptionalInt discoveryPort;
 
-  // Error messages
-  public static String INVALID_NODE_ID_LENGTH =
-      "Invalid node ID: node ID must have exactly 128 hexadecimal characters and should not include any '0x' hex prefix.";
-
   private EnodeURL(
       final BytesValue nodeId,
       final InetAddress address,
@@ -91,7 +87,9 @@ public class EnodeURL {
 
     checkArgument(
         uri.getScheme().equalsIgnoreCase("enode"), "Invalid URI scheme (must equal \"enode\").");
-    checkArgument(NODE_ID_PATTERN.matcher(uri.getUserInfo()).matches(), INVALID_NODE_ID_LENGTH);
+    checkArgument(
+        NODE_ID_PATTERN.matcher(uri.getUserInfo()).matches(),
+        "Invalid node ID: node ID must have exactly 128 hexadecimal characters and should not include any '0x' hex prefix.");
 
     final BytesValue id = BytesValue.fromHexString(uri.getUserInfo());
     String host = uri.getHost();
diff --git a/util/src/test/java/tech/pegasys/pantheon/util/enode/EnodeURLTest.java b/util/src/test/java/tech/pegasys/pantheon/util/enode/EnodeURLTest.java
index f3bb88910f..41251eed19 100644
--- a/util/src/test/java/tech/pegasys/pantheon/util/enode/EnodeURLTest.java
+++ b/util/src/test/java/tech/pegasys/pantheon/util/enode/EnodeURLTest.java
@@ -374,7 +374,8 @@ public class EnodeURLTest {
         String.format("enode://%s@%s:%d", VALID_NODE_ID.substring(1), IPV4_ADDRESS, P2P_PORT);
     assertThatThrownBy(() -> EnodeURL.fromString(invalidEnodeURL))
         .isInstanceOf(IllegalArgumentException.class)
-        .hasMessageContaining("node ID must have exactly 128 hexadecimal");
+        .hasMessageEndingWith(
+            "Invalid node ID: node ID must have exactly 128 hexadecimal characters and should not include any '0x' hex prefix.");
   }
 
   @Test