diff --git a/api/sixtyfps-cpp/include/sixtyfps.h b/api/sixtyfps-cpp/include/sixtyfps.h
index f972ef0a4..11473928d 100644
--- a/api/sixtyfps-cpp/include/sixtyfps.h
+++ b/api/sixtyfps-cpp/include/sixtyfps.h
@@ -427,6 +427,7 @@ private:
     std::vector<private_api::ModelPeer> peers;
 };
 
+namespace private_api {
 /// A Model backed by a std::array of constant size
 template<int Count, typename ModelData>
 class ArrayModel : public Model<ModelData>
@@ -459,6 +460,7 @@ struct IntModel : Model<int>
     int row_count() const override { return data; }
     int row_data(int value) const override { return value; }
 };
+} // namespace pricate_api
 
 /// A Model backed by a SharedVector
 template<typename ModelData>
diff --git a/api/sixtyfps-cpp/include/sixtyfps_callbacks.h b/api/sixtyfps-cpp/include/sixtyfps_callbacks.h
index 5edefbe5c..07d56c15d 100644
--- a/api/sixtyfps-cpp/include/sixtyfps_callbacks.h
+++ b/api/sixtyfps-cpp/include/sixtyfps_callbacks.h
@@ -11,7 +11,7 @@ LICENSE END */
 #include <tuple>
 #include "sixtyfps_properties_internal.h"
 
-namespace sixtyfps {
+namespace sixtyfps::private_api {
 
 /// A Callback stores a function pointer with no parameters and no return value.
 /// It's possible to set that pointer via set_handler() and it can be invoked via call(). This is
@@ -102,7 +102,6 @@ private:
     cbindgen_private::CallbackOpaque inner;
 };
 
-namespace private_api {
 template<typename A, typename R>
 struct CallbackSignatureHelper
 {
@@ -115,6 +114,5 @@ struct CallbackSignatureHelper<void, R>
 };
 template<typename A, typename R = void>
 using CallbackHelper = Callback<typename CallbackSignatureHelper<A, R>::Result>;
-}
 
 } // namespace sixtyfps
diff --git a/sixtyfps_compiler/generator/cpp.rs b/sixtyfps_compiler/generator/cpp.rs
index 15c6282f3..c6ee7ee34 100644
--- a/sixtyfps_compiler/generator/cpp.rs
+++ b/sixtyfps_compiler/generator/cpp.rs
@@ -476,7 +476,7 @@ fn handle_repeater(
     if repeated.is_conditional_element {
         // bool converts to int
         // FIXME: don't do a heap allocation here
-        model = format!("std::make_shared<sixtyfps::IntModel>({})", model)
+        model = format!("std::make_shared<sixtyfps::private_api::IntModel>({})", model)
     };
 
     // FIXME: optimize  if repeated.model.is_constant()
@@ -715,7 +715,7 @@ fn generate_component(
                     }),
                 ));
             }
-            format!("sixtyfps::Callback<{}({})>", return_type, param_types.join(", "))
+            format!("sixtyfps::private_api::Callback<{}({})>", return_type, param_types.join(", "))
         } else {
             let cpp_type = get_cpp_type(&property_decl.property_type, property_decl, diag);
 
@@ -1496,7 +1496,7 @@ fn compile_expression(
                     format!("sixtyfps::SharedString::from_number({})", f)
                 }
                 (Type::Float32, Type::Model) | (Type::Int32, Type::Model) => {
-                    format!("std::make_shared<sixtyfps::IntModel>({})", f)
+                    format!("std::make_shared<sixtyfps::private_api::IntModel>({})", f)
                 }
                 (Type::Array(_), Type::Model) => f,
                 (Type::Float32, Type::Color) => {
@@ -1651,7 +1651,7 @@ fn compile_expression(
         Expression::Array { element_ty, values } => {
             let ty = element_ty.cpp_type().unwrap_or_else(|| "FIXME: report error".to_owned());
             format!(
-                "std::make_shared<sixtyfps::ArrayModel<{count},{ty}>>({val})",
+                "std::make_shared<sixtyfps::private_api::ArrayModel<{count},{ty}>>({val})",
                 count = values.len(),
                 ty = ty,
                 val = values