diff --git a/jooby/src/main/java/io/jooby/internal/RouterImpl.java b/jooby/src/main/java/io/jooby/internal/RouterImpl.java
index 4c7819e191..a93b96fa38 100644
--- a/jooby/src/main/java/io/jooby/internal/RouterImpl.java
+++ b/jooby/src/main/java/io/jooby/internal/RouterImpl.java
@@ -911,7 +911,8 @@ private void copy(Route src, Route it) {
     it.setExecutorKey(src.getExecutorKey());
     it.setTags(src.getTags());
     it.setDescription(src.getDescription());
-    it.setDecoders(src.getDecoders());
+    // DO NOT COPY: See https://github.com/jooby-project/jooby/issues/3500
+    // it.setDecoders(src.getDecoders());
     it.setMvcMethod(src.getMvcMethod());
     it.setNonBlocking(src.isNonBlocking());
     it.setSummary(src.getSummary());
@@ -983,7 +984,7 @@ private static void override(
       Jooby app = (Jooby) router;
       override(src, app.getRouter(), consumer);
     } else if (router instanceof RouterImpl that) {
-      consumer.accept((RouterImpl) src, that);
+      consumer.accept(src, that);
     }
   }
 
diff --git a/tests/pom.xml b/tests/pom.xml
index 34db24a170..b6e277b2f4 100644
--- a/tests/pom.xml
+++ b/tests/pom.xml
@@ -33,6 +33,11 @@
       <artifactId>jooby-jackson</artifactId>
       <version>${jooby.version}</version>
     </dependency>
+    <dependency>
+      <groupId>io.jooby</groupId>
+      <artifactId>jooby-gson</artifactId>
+      <version>${jooby.version}</version>
+    </dependency>
     <dependency>
       <groupId>io.jooby</groupId>
       <artifactId>jooby-avaje-jsonb</artifactId>
@@ -250,7 +255,6 @@
       <version>1.37</version>
       <scope>test</scope>
     </dependency>
-
   </dependencies>
 
   <build>
diff --git a/tests/src/test/java/io/jooby/i3400/Issue3400.java b/tests/src/test/java/io/jooby/i3400/Issue3400.java
new file mode 100644
index 0000000000..7c3a49a664
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3400/Issue3400.java
@@ -0,0 +1,45 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package io.jooby.i3400;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import io.jooby.Jooby;
+import io.jooby.jackson.JacksonModule;
+import io.jooby.junit.ServerTest;
+import io.jooby.junit.ServerTestRunner;
+import okhttp3.MediaType;
+import okhttp3.RequestBody;
+
+public class Issue3400 {
+
+  static class AppA extends Jooby {
+    {
+      post("/pets", ctx -> ctx.body(Pet3400.class));
+    }
+  }
+
+  @ServerTest
+  public void shouldShareDecodersOnMountedResources(ServerTestRunner runner) {
+    runner
+        .define(
+            app -> {
+              app.install(new JacksonModule());
+              app.mount(new AppA());
+            })
+        .ready(
+            http -> {
+              http.post(
+                  "/pets",
+                  RequestBody.create(
+                      "{\"id\": 1, \"name\": \"Cheddar\"}", MediaType.parse("application/json")),
+                  rsp -> {
+                    assertEquals("{\"id\":1,\"name\":\"Cheddar\"}", rsp.body().string());
+                    assertEquals("application/json;charset=UTF-8", rsp.header("Content-Type"));
+                  });
+            });
+  }
+}
diff --git a/tests/src/test/java/io/jooby/i3400/Pet3400.java b/tests/src/test/java/io/jooby/i3400/Pet3400.java
new file mode 100644
index 0000000000..a7fbb20a4f
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3400/Pet3400.java
@@ -0,0 +1,32 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package io.jooby.i3400;
+
+public class Pet3400 {
+  private int id;
+  private String name;
+
+  public Pet3400(int id, String name) {
+    this.id = id;
+    this.name = name;
+  }
+
+  public int getId() {
+    return id;
+  }
+
+  public void setId(int id) {
+    this.id = id;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+}
diff --git a/tests/src/test/java/io/jooby/i3500/Issue3500.java b/tests/src/test/java/io/jooby/i3500/Issue3500.java
new file mode 100644
index 0000000000..85fecbc6b6
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3500/Issue3500.java
@@ -0,0 +1,37 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package io.jooby.i3500;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import io.jooby.junit.ServerTest;
+import io.jooby.junit.ServerTestRunner;
+import okhttp3.MediaType;
+import okhttp3.RequestBody;
+
+public class Issue3500 {
+
+  @ServerTest
+  public void shouldShareDecodersOnMountedResources(ServerTestRunner runner) {
+    runner
+        .use(WidgetService::new)
+        .ready(
+            http -> {
+              http.post(
+                  "/api/widgets1",
+                  RequestBody.create("{\"id\": 1}", MediaType.get("application/json")),
+                  rsp -> {
+                    assertEquals(201, rsp.code());
+                  });
+              http.post(
+                  "/api/widgets2",
+                  RequestBody.create("{\"id\": 1}", MediaType.get("application/json")),
+                  rsp -> {
+                    assertEquals(201, rsp.code());
+                  });
+            });
+  }
+}
diff --git a/tests/src/test/java/io/jooby/i3500/Widget.java b/tests/src/test/java/io/jooby/i3500/Widget.java
new file mode 100644
index 0000000000..e2ad4a7a5b
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3500/Widget.java
@@ -0,0 +1,18 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package io.jooby.i3500;
+
+public class Widget {
+  private int id;
+
+  public int getId() {
+    return id;
+  }
+
+  public void setId(int id) {
+    this.id = id;
+  }
+}
diff --git a/tests/src/test/java/io/jooby/i3500/WidgetService.java b/tests/src/test/java/io/jooby/i3500/WidgetService.java
new file mode 100644
index 0000000000..59330c3ce9
--- /dev/null
+++ b/tests/src/test/java/io/jooby/i3500/WidgetService.java
@@ -0,0 +1,44 @@
+/*
+ * Jooby https://jooby.io
+ * Apache License Version 2.0 https://jooby.io/LICENSE.txt
+ * Copyright 2014 Edgar Espina
+ */
+package io.jooby.i3500;
+
+import io.jooby.Jooby;
+import io.jooby.StatusCode;
+import io.jooby.gson.GsonModule;
+
+public class WidgetService extends Jooby {
+
+  public WidgetService() {
+    install(new GsonModule());
+
+    post(
+        "/api/widgets1",
+        ctx -> {
+          Widget widget = ctx.body().to(Widget.class);
+          System.out.println("Created " + widget);
+          return ctx.send(StatusCode.CREATED);
+        });
+
+    mount(new WidgetRouter());
+  }
+
+  public static void main(String[] args) {
+    new WidgetService().start();
+  }
+}
+
+class WidgetRouter extends Jooby {
+
+  public WidgetRouter() {
+
+    post(
+        "/api/widgets2",
+        ctx -> {
+          Widget widget = ctx.body().to(Widget.class);
+          return ctx.send(StatusCode.CREATED);
+        });
+  }
+}