diff --git a/smallrye-reactive-messaging-provider/src/main/java/io/smallrye/reactive/messaging/providers/impl/InternalChannelRegistry.java b/smallrye-reactive-messaging-provider/src/main/java/io/smallrye/reactive/messaging/providers/impl/InternalChannelRegistry.java
index a06929b05e..2ffe332f57 100644
--- a/smallrye-reactive-messaging-provider/src/main/java/io/smallrye/reactive/messaging/providers/impl/InternalChannelRegistry.java
+++ b/smallrye-reactive-messaging-provider/src/main/java/io/smallrye/reactive/messaging/providers/impl/InternalChannelRegistry.java
@@ -3,7 +3,6 @@
 import static io.smallrye.reactive.messaging.providers.i18n.ProviderMessages.msg;
 
 import java.util.*;
-import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Flow;
 import java.util.stream.Collectors;
 
@@ -18,13 +17,13 @@
 @ApplicationScoped
 public class InternalChannelRegistry implements ChannelRegistry {
 
-    private final Map<String, List<Flow.Publisher<? extends Message<?>>>> publishers = new ConcurrentHashMap<>();
-    private final Map<String, List<Flow.Subscriber<? extends Message<?>>>> subscribers = new ConcurrentHashMap<>();
+    private final Map<String, List<Flow.Publisher<? extends Message<?>>>> publishers = new HashMap<>();
+    private final Map<String, List<Flow.Subscriber<? extends Message<?>>>> subscribers = new HashMap<>();
 
-    private final Map<String, Boolean> outgoing = new ConcurrentHashMap<>();
-    private final Map<String, Boolean> incoming = new ConcurrentHashMap<>();
+    private final Map<String, Boolean> outgoing = new HashMap<>();
+    private final Map<String, Boolean> incoming = new HashMap<>();
 
-    private final Map<Class<?>, Map<String, Object>> emitters = new ConcurrentHashMap<>();
+    private final Map<Class<?>, Map<String, Object>> emitters = new HashMap<>();
 
     @Override
     public Flow.Publisher<? extends Message<?>> register(String name,
@@ -37,7 +36,7 @@ public Flow.Publisher<? extends Message<?>> register(String name,
     }
 
     @Override
-    public Flow.Subscriber<? extends Message<?>> register(String name,
+    public synchronized Flow.Subscriber<? extends Message<?>> register(String name,
             Flow.Subscriber<? extends Message<?>> subscriber, boolean merge) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         Objects.requireNonNull(subscriber, msg.subscriberMustBeSet());
@@ -47,21 +46,21 @@ public Flow.Subscriber<? extends Message<?>> register(String name,
     }
 
     @Override
-    public void register(String name, Emitter<?> emitter) {
+    public synchronized void register(String name, Emitter<?> emitter) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         Objects.requireNonNull(emitter, msg.emitterMustBeSet());
         register(name, Emitter.class, emitter);
     }
 
     @Override
-    public void register(String name, MutinyEmitter<?> emitter) {
+    public synchronized void register(String name, MutinyEmitter<?> emitter) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         Objects.requireNonNull(emitter, msg.emitterMustBeSet());
         register(name, MutinyEmitter.class, emitter);
     }
 
     @Override
-    public <T> void register(String name, Class<T> emitterType, T emitter) {
+    public synchronized <T> void register(String name, Class<T> emitterType, T emitter) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         Objects.requireNonNull(emitter, msg.emitterMustBeSet());
         Map<String, Object> map = emitters.computeIfAbsent(emitterType, key -> new HashMap<>());
@@ -69,26 +68,25 @@ public <T> void register(String name, Class<T> emitterType, T emitter) {
     }
 
     @Override
-    public List<Flow.Publisher<? extends Message<?>>> getPublishers(String name) {
+    public synchronized List<Flow.Publisher<? extends Message<?>>> getPublishers(String name) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         return publishers.getOrDefault(name, Collections.emptyList());
     }
 
     @Override
-    public Emitter<?> getEmitter(String name) {
+    public synchronized Emitter<?> getEmitter(String name) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         return getEmitter(name, Emitter.class);
     }
 
     @Override
-    public MutinyEmitter<?> getMutinyEmitter(String name) {
+    public synchronized MutinyEmitter<?> getMutinyEmitter(String name) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         return getEmitter(name, MutinyEmitter.class);
     }
 
-    @SuppressWarnings("unchecked")
     @Override
-    public <T> T getEmitter(String name, Class<? super T> emitterType) {
+    public synchronized <T> T getEmitter(String name, Class<? super T> emitterType) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         Map<String, Object> typedEmitters = emitters.get(emitterType);
         if (typedEmitters == null) {
@@ -99,7 +97,7 @@ public <T> T getEmitter(String name, Class<? super T> emitterType) {
     }
 
     @Override
-    public List<Flow.Subscriber<? extends Message<?>>> getSubscribers(String name) {
+    public synchronized List<Flow.Subscriber<? extends Message<?>>> getSubscribers(String name) {
         Objects.requireNonNull(name, msg.nameMustBeSet());
         return subscribers.getOrDefault(name, Collections.emptyList());
     }
@@ -110,17 +108,17 @@ private <T> void register(Map<String, List<T>> multimap, String name, T item) {
     }
 
     @Override
-    public Set<String> getIncomingNames() {
-        return publishers.keySet();
+    public synchronized Set<String> getIncomingNames() {
+        return new HashSet<>(publishers.keySet());
     }
 
     @Override
-    public Set<String> getOutgoingNames() {
-        return subscribers.keySet();
+    public synchronized Set<String> getOutgoingNames() {
+        return new HashSet<>(subscribers.keySet());
     }
 
     @Override
-    public Set<String> getEmitterNames() {
+    public synchronized Set<String> getEmitterNames() {
         return emitters.values().stream().flatMap(m -> m.keySet().stream()).collect(Collectors.toSet());
     }