diff --git a/crates/fj/src/handle_model.rs b/crates/fj/src/handle_model.rs
index 7d8f1e1fb5..847fa598c8 100644
--- a/crates/fj/src/handle_model.rs
+++ b/crates/fj/src/handle_model.rs
@@ -6,8 +6,8 @@ use fj_core::{
         bounding_volume::BoundingVolume,
         triangulate::Triangulate,
     },
-    services::Services,
     validate::ValidationErrors,
+    Instance,
 };
 use fj_interop::Model;
 use fj_math::{Aabb, Point, Scalar};
@@ -23,7 +23,7 @@ use crate::Args;
 ///
 /// This function is used by Fornjot's own testing infrastructure, but is useful
 /// beyond that, when using Fornjot directly to define a model.
-pub fn handle_model<M>(model: &M, services: Services) -> Result
+pub fn handle_model<M>(model: &M, core: Instance) -> Result
 where
     for<'r> (&'r M, Tolerance): Triangulate,
     M: BoundingVolume<3>,
@@ -36,9 +36,9 @@ where
     let args = Args::parse();
 
     if args.ignore_validation {
-        mem::forget(services);
+        mem::forget(core);
     } else {
-        services.drop_and_validate()?;
+        core.services.drop_and_validate()?;
     }
 
     let aabb = model.aabb().unwrap_or(Aabb {
diff --git a/models/all/src/main.rs b/models/all/src/main.rs
index c7f3746adf..767196187a 100644
--- a/models/all/src/main.rs
+++ b/models/all/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = all::model(&mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/color/src/main.rs b/models/color/src/main.rs
index 845c2f79e7..909d527def 100644
--- a/models/color/src/main.rs
+++ b/models/color/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = color::model(&mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/cuboid/src/main.rs b/models/cuboid/src/main.rs
index 9aa0752a75..290a2fbd6a 100644
--- a/models/cuboid/src/main.rs
+++ b/models/cuboid/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = cuboid::model([3., 2., 1.], &mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/holes/src/main.rs b/models/holes/src/main.rs
index 984b3515b5..192b653971 100644
--- a/models/holes/src/main.rs
+++ b/models/holes/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = holes::model(0.25, &mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/spacer/src/main.rs b/models/spacer/src/main.rs
index 4d8a3e3b2c..a6d19176ec 100644
--- a/models/spacer/src/main.rs
+++ b/models/spacer/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = spacer::model(1., 0.5, 1., &mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/split/src/main.rs b/models/split/src/main.rs
index 52c9ca979b..7817bdbdaa 100644
--- a/models/split/src/main.rs
+++ b/models/split/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = split::model(1.0, 0.2, &mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/star/src/main.rs b/models/star/src/main.rs
index 7318f7a091..cc8a8b2114 100644
--- a/models/star/src/main.rs
+++ b/models/star/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = star::model(5, 1., 2., 1., &mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }
diff --git a/models/vertices-indices/src/main.rs b/models/vertices-indices/src/main.rs
index 7b4550bf22..84d0b4bc07 100644
--- a/models/vertices-indices/src/main.rs
+++ b/models/vertices-indices/src/main.rs
@@ -3,6 +3,6 @@ use fj::handle_model;
 fn main() -> fj::Result {
     let mut core = fj::core::Instance::new();
     let model = vertices_indices::model(&mut core);
-    handle_model(&model, core.services)?;
+    handle_model(&model, core)?;
     Ok(())
 }