diff --git a/src/main/java/net/openhft/chronicle/map/ChannelProvider.java b/src/main/java/net/openhft/chronicle/map/ChannelProvider.java
index 9d37dfa06..684dff7d3 100644
--- a/src/main/java/net/openhft/chronicle/map/ChannelProvider.java
+++ b/src/main/java/net/openhft/chronicle/map/ChannelProvider.java
@@ -501,8 +501,6 @@ final class ChannelProvider implements Closeable {
 
         @Override
         public void close() throws IOException {
-            // synchronized on parent instance to prevent possible (but very unlikely) contention
-            // between close() calls on different channels
             channelDataLock.writeLock().lock();
             try {
                 chronicleChannelList.remove(chronicleChannels[chronicleChannel]);
diff --git a/src/main/java/net/openhft/chronicle/map/InstanceConfig.java b/src/main/java/net/openhft/chronicle/map/InstanceConfig.java
index e73d2778a..5e75a6492 100644
--- a/src/main/java/net/openhft/chronicle/map/InstanceConfig.java
+++ b/src/main/java/net/openhft/chronicle/map/InstanceConfig.java
@@ -32,6 +32,8 @@ final class InstanceConfig<K, V>
     final ReplicationChannel channel;
     final File file;
 
+    private boolean used = false;
+
     InstanceConfig(AbstractChronicleMapBuilder<K, V, ?> mapBuilder,
                    SingleChronicleHashReplication singleHashReplication,
                    ReplicationChannel channel,
@@ -67,7 +69,15 @@ final class InstanceConfig<K, V>
     }
 
     @Override
-    public ChronicleMap<K, V> create() throws IOException {
+    public synchronized ChronicleMap<K, V> create() throws IOException {
+        if (used)
+            throw new IllegalStateException(
+                    "A ChronicleMap has already been created using this instance config. " +
+                            "Create a new instance config (builder.instance() or call any " +
+                            "configuration method on this instance config) to create a new " +
+                            "ChronicleMap instance");
+        used = true;
         return mapBuilder.create(this);
     }
+
 }
diff --git a/src/main/java/net/openhft/chronicle/set/InstanceConfig.java b/src/main/java/net/openhft/chronicle/set/InstanceConfig.java
index e7fe620c4..9d3f43f6c 100644
--- a/src/main/java/net/openhft/chronicle/set/InstanceConfig.java
+++ b/src/main/java/net/openhft/chronicle/set/InstanceConfig.java
@@ -29,6 +29,8 @@ final class InstanceConfig<E> implements ChronicleHashInstanceConfig<ChronicleSe
 
     private final ChronicleHashInstanceConfig<ChronicleMap<E, DummyValue>> mapConfig;
 
+    private boolean used;
+
     InstanceConfig(ChronicleHashInstanceConfig<ChronicleMap<E, DummyValue>> mapConfig) {
         this.mapConfig = mapConfig;
     }
@@ -56,7 +58,14 @@ final class InstanceConfig<E> implements ChronicleHashInstanceConfig<ChronicleSe
     }
 
     @Override
-    public ChronicleSet<E> create() throws IOException {
+    public synchronized ChronicleSet<E> create() throws IOException {
+        if (used)
+            throw new IllegalStateException(
+                    "A ChronicleSet has already been created using this instance config. " +
+                            "Create a new instance config (builder.instance() or call any " +
+                            "configuration method on this instance config) to create a new " +
+                            "ChronicleSet instance");
+        used = true;
         return new SetFromMap<>(mapConfig.create());
     }
 }