diff --git a/src/main/java/net/openhft/chronicle/map/SerializationBuilder.java b/src/main/java/net/openhft/chronicle/map/SerializationBuilder.java
index 7f1bec3df..4da9a5f97 100644
--- a/src/main/java/net/openhft/chronicle/map/SerializationBuilder.java
+++ b/src/main/java/net/openhft/chronicle/map/SerializationBuilder.java
@@ -309,7 +309,7 @@ final class SerializationBuilder<E> implements Cloneable, Serializable {
         }
         // set max size once more, because current maxSize could be x64 or x2 larger than needed
         maxSize(constantSize);
-        sizeMarshaller(SizeMarshallers.constant(constantSize));
+        sizeMarshaller(net.openhft.chronicle.hash.serialization.SizeMarshallers.constant(constantSize));
         return this;
     }
 
diff --git a/src/main/java/net/openhft/chronicle/map/TcpReplicator.java b/src/main/java/net/openhft/chronicle/map/TcpReplicator.java
index ffcc12f14..6c0e060b8 100644
--- a/src/main/java/net/openhft/chronicle/map/TcpReplicator.java
+++ b/src/main/java/net/openhft/chronicle/map/TcpReplicator.java
@@ -32,6 +32,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.Closeable;
+import java.io.EOFException;
 import java.io.IOException;
 import java.net.*;
 import java.nio.BufferUnderflowException;
@@ -509,11 +510,44 @@ final class TcpReplicator<K, V> extends AbstractChannelReplicator implements Clo
     }
 
 
+    /**
+     * check that the version number is valid text,
+     *
+     * @param versionNumber the version number to check
+     * @return true, if the version number looks correct
+     */
+    boolean isValidVersionNumber(String versionNumber) {
+
+        if (versionNumber.length()<=2)
+            return false;
+
+        for (char c : versionNumber.toCharArray()) {
+
+            if (c >= '0' && c <= '9')
+                continue;
+
+            if (c == '.' || c == '-' || c == '_')
+                continue;
+
+            if (c >= 'A' && c <= 'Z')
+                continue;
+
+            if (c >= 'a' && c <= 'z')
+                continue;
+
+            return false;
+
+        }
+
+        return true;
+    }
+
     private void checkVersions(final Attached<K, V> attached) {
 
         final String localVersion = BuildVersion.version();
         final String remoteVersion = attached.serverVersion;
 
+
         if (!remoteVersion.equals(localVersion)) {
             byte remoteIdentifier = attached.remoteIdentifier;
             LOG.warn("DIFFERENT CHRONICLE-MAP VERSIONS : " +
@@ -610,10 +644,21 @@ final class TcpReplicator<K, V> extends AbstractChannelReplicator implements Clo
         }
 
         if (attached.serverVersion == null) {
-            attached.serverVersion = reader.readRemoteServerVersion();
+            try {
+                attached.serverVersion = reader.readRemoteServerVersion();
+            } catch (IllegalStateException e1) {
+                socketChannel.close();
+            }
+
             if (attached.serverVersion == null)
                 return;
 
+            if (!isValidVersionNumber(attached.serverVersion)) {
+                LOG.warn("Please check that you don't have a third party system incorrectly connecting to ChronicleMap, " +
+                        "Closing the remote connection as Chronicle can not make sense of the remote version number received from the external connection, version="+attached.serverVersion+", Chronicle is expecting the version number to only contain '.',A-Z,a-z,0-9");
+                socketChannel.close();
+            }
+
             checkVersions(attached);
         }
 
diff --git a/src/test/java/net/openhft/chronicle/map/TCPSocketReplicationTest.java b/src/test/java/net/openhft/chronicle/map/TCPSocketReplicationTest.java
index 62ed81f0b..d9d8e407e 100644
--- a/src/test/java/net/openhft/chronicle/map/TCPSocketReplicationTest.java
+++ b/src/test/java/net/openhft/chronicle/map/TCPSocketReplicationTest.java
@@ -97,6 +97,8 @@ public class TCPSocketReplicationTest {
 
         assertEquals(map1, map2);
         assertTrue(!map1.isEmpty());
+
+        Thread.sleep(9999999);
     }
 
     @Test