diff --git a/checker/tests/mustcall/FunctionalInterfaces.java b/checker/tests/mustcall/FunctionalInterfaces.java
new file mode 100644
index 00000000000..b556623ffa5
--- /dev/null
+++ b/checker/tests/mustcall/FunctionalInterfaces.java
@@ -0,0 +1,52 @@
+// Test that the correct type is assigned to instantiations of functional
+// interfaces.
+// https://github.com/typetools/checker-framework/issues/6823
+
+import java.io.Closeable;
+import org.checkerframework.checker.mustcall.qual.*;
+
+public abstract class FunctionalInterfaces {
+
+  @FunctionalInterface
+  public interface Actor extends Closeable {
+    void act();
+
+    @Override
+    default void close() {}
+  }
+
+  public static class ActorImpl implements Actor {
+    @Override
+    public void act() {}
+  }
+
+  public abstract void run(@MustCall({}) Actor a);
+
+  public static void method() {}
+
+  public void normalConstruction() {
+
+    // :: error: (assignment)
+    @MustCall({}) Actor a = new ActorImpl();
+  }
+
+  public void inlineClass() {
+
+    class ActorImplInline implements Actor {
+      @Override
+      public void act() {}
+    }
+
+    // :: error: (assignment)
+    @MustCall({}) Actor a = new ActorImplInline();
+  }
+
+  public void anonymousClass() {
+
+    @MustCall({}) Actor a =
+        // :: error: (assignment)
+        new Actor() {
+          public void act() {}
+        };
+  }
+}
diff --git a/framework/src/main/java/org/checkerframework/framework/type/AnnotatedTypeFactory.java b/framework/src/main/java/org/checkerframework/framework/type/AnnotatedTypeFactory.java
index d0b39de5baf..f61a85ddd26 100644
--- a/framework/src/main/java/org/checkerframework/framework/type/AnnotatedTypeFactory.java
+++ b/framework/src/main/java/org/checkerframework/framework/type/AnnotatedTypeFactory.java
@@ -2826,7 +2826,13 @@ protected ParameterizedExecutableType constructorFromUse(
         p.addAll(1, superCon.getParameterTypes());
         con.setParameterTypes(p);
       }
-      con.getReturnType().replaceAnnotations(superCon.getReturnType().getPrimaryAnnotations());
+      Set<? extends AnnotationMirror> lub =
+          qualHierarchy.leastUpperBoundsShallow(
+              type.getPrimaryAnnotations(),
+              type.getUnderlyingType(),
+              superCon.getReturnType().getPrimaryAnnotations(),
+              superCon.getReturnType().getUnderlyingType());
+      con.getReturnType().replaceAnnotations(lub);
     } else {
       con = AnnotatedTypes.asMemberOf(types, this, type, ctor, con);
     }
diff --git a/framework/tests/h1h2checker/AnonymousClasses.java b/framework/tests/h1h2checker/AnonymousClasses.java
index 3caa087de6a..b373de987cb 100644
--- a/framework/tests/h1h2checker/AnonymousClasses.java
+++ b/framework/tests/h1h2checker/AnonymousClasses.java
@@ -4,7 +4,7 @@
 
 public class AnonymousClasses {
   private <@H1S1 T extends @H1S1 Comparator<T>> void testGenericAnonymous() {
-    // :: error: (type.argument) :: error: (constructor.invocation)
+    // :: error: (type.argument) :: warning: (cast.unsafe.constructor.invocation)
     new @H1S1 Gen<T>() {};
     // :: error: (type.argument) :: warning: (cast.unsafe.constructor.invocation)
     new @H1S1 GenInter<T>() {};