diff --git a/include/wx/weakref.h b/include/wx/weakref.h
index b767cafd0a..08878903f4 100644
--- a/include/wx/weakref.h
+++ b/include/wx/weakref.h
@@ -149,7 +149,7 @@ protected:
         DoAssign( pobj, ptbase );
     }
 
-#ifdef HAVE_DYNAMIC_CAST
+#ifndef wxNO_RTTI
     void AssignHelper(T* pobj, wxInt2Type<false>)
     {
         // A last way to get a trackable pointer
@@ -165,7 +165,7 @@ protected:
             Release();
         }
     }
-#endif // HAVE_DYNAMIC_CAST
+#endif // RTTI enabled
 
     void AssignCopy(const wxWeakRefImpl& wr)
     {
@@ -254,7 +254,7 @@ public:
 };
 
 
-#ifdef HAVE_DYNAMIC_CAST
+#ifndef wxNO_RTTI
 
 // Weak ref implementation assign objects are queried for wxTrackable
 // using dynamic_cast<>
@@ -338,7 +338,7 @@ protected:
     T *m_pobj;
 };
 
-#endif // #ifdef HAVE_DYNAMIC_CAST
+#endif // RTTI enabled
 
 
 // Provide some basic types of weak references
diff --git a/tests/weakref/weakref.cpp b/tests/weakref/weakref.cpp
index ef1b8ad0f8..163a16f401 100644
--- a/tests/weakref/weakref.cpp
+++ b/tests/weakref/weakref.cpp
@@ -76,6 +76,14 @@ CPPUNIT_TEST_SUITE_REGISTRATION( WeakRefTestCase );
 // also include in it's own registry so that these tests can be run alone
 CPPUNIT_TEST_SUITE_NAMED_REGISTRATION( WeakRefTestCase, "WeakRefTestCase" );
 
+
+// Test weak reference to an incomplete type, this should work if the type is
+// fully defined before it is used (but currently doesn't, see #11916)
+struct ForwardDeclaredClass;
+wxWeakRef<ForwardDeclaredClass> g_incompleteWeakRef;
+
+struct ForwardDeclaredClass : wxEvtHandler { };
+
 void WeakRefTestCase::DeclareTest()
 {
     {
@@ -110,6 +118,17 @@ void WeakRefTestCase::DeclareTest()
         CPPUNIT_ASSERT( wreh.get() == &eh );
         CPPUNIT_ASSERT( wrot.get() == &ot );
     }
+
+    // This test requires a working dynamic_cast<>
+#ifndef wxNO_RTTI
+    {
+        ForwardDeclaredClass fdc;
+        g_incompleteWeakRef = &fdc;
+        CPPUNIT_ASSERT( g_incompleteWeakRef );
+    }
+
+    CPPUNIT_ASSERT( !g_incompleteWeakRef );
+#endif // RTTI enabled
 }
 
 void WeakRefTestCase::AssignTest()