diff --git a/net/api/src/main/java/org/onlab/onos/net/provider/AbstractProviderBroker.java b/net/api/src/main/java/org/onlab/onos/net/provider/AbstractProviderBroker.java
index a783fec..ad1e0ab 100644
--- a/net/api/src/main/java/org/onlab/onos/net/provider/AbstractProviderBroker.java
+++ b/net/api/src/main/java/org/onlab/onos/net/provider/AbstractProviderBroker.java
@@ -38,10 +38,9 @@
     public synchronized void unregister(P provider) {
         checkNotNull(provider, "Provider cannot be null");
         S service = services.get(provider);
-        checkArgument(service != null, "Provider %s not registered", provider.id());
-        if (service instanceof AbstractProviderService) {
+        if (service != null && service instanceof AbstractProviderService) {
             ((AbstractProviderService) service).invalidate();
+            services.remove(provider);
         }
-        services.remove(provider);
     }
 }
diff --git a/net/api/src/main/java/org/onlab/onos/net/provider/ProviderBroker.java b/net/api/src/main/java/org/onlab/onos/net/provider/ProviderBroker.java
index a8e294e..438fdb7 100644
--- a/net/api/src/main/java/org/onlab/onos/net/provider/ProviderBroker.java
+++ b/net/api/src/main/java/org/onlab/onos/net/provider/ProviderBroker.java
@@ -13,6 +13,7 @@
      *
      * @param provider provider to be registered
      * @return provider service for injecting information into core
+     * @throws java.lang.IllegalArgumentException if the provider is registered already
      */
     S register(P provider);
 
@@ -20,6 +21,9 @@
      * Unregisters the supplied provider. As a result the previously issued
      * provider service will be invalidated and any subsequent invocations
      * of its methods may throw {@link java.lang.IllegalStateException}.
+     * <p/>
+     * Unregistering a provider that has not been previously registered results
+     * in a no-op.
      *
      * @param provider provider to be unregistered
      */