diff --git a/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateEntityEnhancer.java b/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateEntityEnhancer.java
index 70a00a31ac531..80b6eea0e4376 100644
--- a/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateEntityEnhancer.java
+++ b/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateEntityEnhancer.java
@@ -17,6 +17,7 @@
 import io.quarkus.hibernate.orm.deployment.integration.QuarkusClassFileLocator;
 import io.quarkus.hibernate.orm.deployment.integration.QuarkusEnhancementContext;
 import net.bytebuddy.ClassFileVersion;
+import net.bytebuddy.dynamic.ClassFileLocator;
 
 /**
  * Used to transform bytecode by registering to
@@ -101,8 +102,9 @@ public Enhancer getEnhancer() {
             if (actualEnhancer == null) {
                 synchronized (this) {
                     if (actualEnhancer == null) {
-                        EnhancerClassLocator modelPool = ModelTypePool.buildModelTypePool(QuarkusClassFileLocator.INSTANCE,
-                                CORE_POOL);
+                        EnhancerClassLocator modelPool = new QuarkusModelTypePool(
+                                ModelTypePool.buildModelTypePool(QuarkusClassFileLocator.INSTANCE,
+                                        CORE_POOL));
                         actualEnhancer = PROVIDER.getEnhancer(QuarkusEnhancementContext.INSTANCE, modelPool);
                     }
                 }
@@ -111,4 +113,41 @@ public Enhancer getEnhancer() {
         }
     }
 
+    //This is most likely better solved within Hibernate ORM, but should do for now:
+    private static class QuarkusModelTypePool implements EnhancerClassLocator {
+
+        private final EnhancerClassLocator delegate;
+
+        private QuarkusModelTypePool(final EnhancerClassLocator delegate) {
+            this.delegate = delegate;
+        }
+
+        @Override
+        public void registerClassNameAndBytes(String s, byte[] bytes) {
+            this.delegate.registerClassNameAndBytes(s, bytes);
+        }
+
+        @Override
+        public void deregisterClassNameAndBytes(String s) {
+            //Don't do this: we'll have concurrent de-registrations, possibly for the same entry being
+            //processed by a different thread, when entities are listed as inner classes of other types
+            //which are also processed. This happens for example in Quarkus integration tests.
+        }
+
+        @Override
+        public ClassFileLocator asClassFileLocator() {
+            return delegate.asClassFileLocator();
+        }
+
+        @Override
+        public Resolution describe(String s) {
+            return delegate.describe(s);
+        }
+
+        @Override
+        public void clear() {
+            //nope
+        }
+    }
+
 }