diff --git a/crates/mun_memory/src/mapping.rs b/crates/mun_memory/src/mapping.rs
index 4f5ec94b..2cfcb6f2 100644
--- a/crates/mun_memory/src/mapping.rs
+++ b/crates/mun_memory/src/mapping.rs
@@ -9,6 +9,7 @@ use crate::{
 use std::collections::{HashMap, HashSet};
 
 /// The type mapping needed to convert an old into a new set of unique and ordered values.
+#[derive(Debug)]
 pub struct Mapping {
     /// The types that were deleted
     pub deletions: HashSet<Type>,
@@ -19,6 +20,7 @@ pub struct Mapping {
 }
 
 /// The struct mapping needed to convert an old into a new struct of unique and ordered fields.
+#[derive(Debug)]
 pub struct StructMapping {
     /// The field mappings for each original struct field
     pub field_mapping: Vec<FieldMapping>,
diff --git a/crates/mun_runtime/tests/hot_reloading.rs b/crates/mun_runtime/tests/hot_reloading.rs
index 78376e98..f4dba6f4 100644
--- a/crates/mun_runtime/tests/hot_reloading.rs
+++ b/crates/mun_runtime/tests/hot_reloading.rs
@@ -1,10 +1,11 @@
 #[macro_use]
 mod util;
 
+use mun_runtime::StructRef;
 use mun_test::CompileAndRunTestDriver;
 
 #[test]
-fn hotreloadable() {
+fn reloadable_function_single_file() {
     let mut driver = CompileAndRunTestDriver::new(
         r"
     pub fn main() -> i32 { 5 }
@@ -14,7 +15,7 @@ fn hotreloadable() {
     .expect("Failed to build test driver");
     assert_invoke_eq!(i32, 5, driver, "main");
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r"
     pub fn main() -> i32 { 10 }
@@ -24,7 +25,37 @@ fn hotreloadable() {
 }
 
 #[test]
-fn hotreload_struct_decl() {
+fn reloadable_function_multi_file() {
+    let mut driver = CompileAndRunTestDriver::from_fixture(
+        r#"
+    //- /mun.toml
+    [package]
+    name="foo"
+    version="0.0.0"
+
+    //- /src/mod.mun
+    use package::foo::bar;
+    pub fn main() -> i32 { bar() }
+
+    //- /src/foo.mun
+    pub fn bar() -> i32 { 5 }
+    "#,
+        |builder| builder,
+    )
+    .expect("Failed to build test driver");
+    assert_invoke_eq!(i32, 5, driver, "main");
+
+    driver.update_file(
+        "foo.mun",
+        r#"
+    pub fn bar() -> i32 { 10 }
+    "#,
+    );
+    assert_invoke_eq!(i32, 10, driver, "main");
+}
+
+#[test]
+fn reloadable_struct_decl_single_file() {
     let mut driver = CompileAndRunTestDriver::new(
         r#"
     pub struct(gc) Args {
@@ -33,18 +64,28 @@ fn hotreload_struct_decl() {
     }
     
     struct(gc) Bar {
-        m: f64,
+        m: i32,
     }
 
     pub fn args() -> Args {
-        Args { n: 3, foo: Bar { m: 1.0 }, }
+        Args { n: 3, foo: Bar { m: 1 }, }
     }
     "#,
         |builder| builder,
     )
     .expect("Failed to build test driver");
 
-    driver.update(
+    let args: StructRef = driver
+        .runtime
+        .invoke("args", ())
+        .expect("Failed to call function");
+
+    let foo: StructRef = args.get("foo").expect("Failed to get struct field");
+    assert_eq!(foo.get::<i32>("m").expect("Failed to get struct field"), 1);
+
+    let foo = foo.root();
+
+    driver.update_file(
         "mod.mun",
         r#"
     pub struct(gc) Args {
@@ -53,7 +94,7 @@ fn hotreload_struct_decl() {
     }
     
     struct(gc) Bar {
-        m: i32,
+        m: i64,
     }
 
     pub fn args() -> Args {
@@ -61,4 +102,71 @@ fn hotreload_struct_decl() {
     }
     "#,
     );
+
+    let foo = foo.as_ref(&driver.runtime);
+    assert_eq!(foo.get::<i64>("m").expect("Failed to get struct field"), 1);
+}
+
+#[test]
+fn reloadable_struct_decl_multi_file() {
+    let mut driver = CompileAndRunTestDriver::from_fixture(
+        r#"
+    //- /mun.toml
+    [package]
+    name="foo"
+    version="0.0.0"
+
+    //- /src/mod.mun
+    use package::foo::Bar;
+    pub struct(gc) Args {
+        n: i32,
+        foo: Bar,
+    }
+
+    pub fn args() -> Args {
+        Args { n: 3, foo: Bar { m: 1 }, }
+    }
+
+    //- /src/foo.mun
+    struct(gc) Bar {
+        m: i64,
+    }
+    "#,
+        |builder| builder,
+    )
+    .expect("Failed to build test driver");
+
+    let args: StructRef = driver
+        .runtime
+        .invoke("args", ())
+        .expect("Failed to call function");
+
+    assert_eq!(args.get::<i32>("n").expect("Failed to get struct field"), 3);
+
+    let foo: StructRef = args.get("foo").expect("Failed to get struct field");
+    assert_eq!(foo.get::<i64>("m").expect("Failed to get struct field"), 1);
+
+    let args = args.root();
+    let foo = foo.root();
+
+    driver.update_file(
+        "mod.mun",
+        r#"
+    use package::foo::Bar;
+    pub struct(gc) Args {
+        n: i64,
+        foo: Bar,
+    }
+
+    pub fn args() -> Args {
+        Args { n: 3, foo: Bar { m: 1 }, }
+    }
+    "#,
+    );
+
+    let args = args.as_ref(&driver.runtime);
+    assert_eq!(args.get::<i64>("n").expect("Failed to get struct field"), 3);
+
+    let foo = foo.as_ref(&driver.runtime);
+    assert_eq!(foo.get::<i64>("m").expect("Failed to get struct field"), 1);
 }
diff --git a/crates/mun_runtime/tests/memory.rs b/crates/mun_runtime/tests/memory.rs
index e8a4ab24..43d76a2f 100644
--- a/crates/mun_runtime/tests/memory.rs
+++ b/crates/mun_runtime/tests/memory.rs
@@ -65,7 +65,7 @@ fn map_struct_insert_field1() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -104,7 +104,7 @@ fn map_struct_insert_field2() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -150,7 +150,7 @@ fn map_struct_insert_field3() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -198,7 +198,7 @@ fn map_struct_remove_field1() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -236,7 +236,7 @@ fn map_struct_remove_field2() {
     let result: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let rooted_result = result.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -277,7 +277,7 @@ fn map_struct_remove_field3() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -319,7 +319,7 @@ fn map_struct_cast_fields1() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d, e)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo(
@@ -373,7 +373,7 @@ fn map_struct_cast_fields2() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a,)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo(
@@ -412,7 +412,7 @@ fn map_struct_swap_fields1() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -462,7 +462,7 @@ fn map_struct_swap_fields2() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -515,7 +515,7 @@ fn map_struct_rename_field1() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -563,7 +563,7 @@ fn map_struct_rename_field2() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -613,7 +613,7 @@ fn map_struct_all() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -667,7 +667,7 @@ fn map_array_to_array_different_array_to_primitive_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -726,7 +726,7 @@ fn map_array_to_array_different_array_to_primitive_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -794,7 +794,7 @@ fn map_array_to_array_different_array_to_struct_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct(gc) Bar(i64);
@@ -868,7 +868,7 @@ fn map_array_to_array_different_array_to_struct_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(i32);
@@ -933,7 +933,7 @@ fn map_array_to_array_different_primitive_to_array_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -996,7 +996,7 @@ fn map_array_to_array_different_primitive_to_array_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1056,7 +1056,7 @@ fn map_array_to_array_different_primitive_to_primitive() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1116,7 +1116,7 @@ fn map_array_to_array_different_primitive_to_struct() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct(gc) Bar(i64);
@@ -1187,7 +1187,7 @@ fn map_array_to_array_different_struct_to_array_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(i64);
@@ -1270,7 +1270,7 @@ fn map_array_to_array_different_struct_to_array_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(i32);
@@ -1353,7 +1353,7 @@ fn map_array_to_array_different_struct_to_struct() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct(gc) Bar(i64);
@@ -1420,7 +1420,7 @@ fn map_array_to_array_same_primitive() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1475,7 +1475,7 @@ fn map_array_to_array_same_struct() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(f64);
@@ -1538,7 +1538,7 @@ fn map_array_to_primitive_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1588,7 +1588,7 @@ fn map_array_to_primitive_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1643,7 +1643,7 @@ fn map_array_to_struct_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct(gc) Bar(f64);
@@ -1711,7 +1711,7 @@ fn map_array_to_struct_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct(gc) Bar(f32);
@@ -1776,7 +1776,7 @@ fn map_primitive_to_array_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1840,7 +1840,7 @@ fn map_primitive_to_array_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c, d)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Foo {
@@ -1910,7 +1910,7 @@ fn map_struct_to_array_same() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(f64);
@@ -1975,7 +1975,7 @@ fn map_struct_to_array_different() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(f64);
@@ -2036,7 +2036,7 @@ fn insert_array() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Foo {
@@ -2084,7 +2084,7 @@ fn delete_used_struct() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, b, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         pub struct Bar(i64);
@@ -2163,7 +2163,7 @@ fn nested_structs() {
     let value_wrapper = value_wrapper.root();
 
     // Tests mapping of `gc -> gc`, `value -> value`
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
     pub struct(gc) GcStruct(f64, f64);
@@ -2203,7 +2203,7 @@ fn nested_structs() {
     assert_eq!(value_1.get::<f64>("1"), Ok(b.into()));
 
     // Tests an identity mapping
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
     pub struct(gc) GcStruct(f64, f64);
@@ -2248,7 +2248,7 @@ fn nested_structs() {
     let value_1 = value_1.root();
 
     // Tests mapping of `gc -> value`, `value -> gc`
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
     struct(value) GcStruct(f64, f64);
@@ -2285,7 +2285,7 @@ fn nested_structs() {
 
     // Tests mapping of different struct type, when `gc -> value`, `value -> gc`, and
     // retention of an old library (due to removal of `GcStruct` and `ValueStruct`)
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
     struct(gc) GcStruct2(f64);
@@ -2356,7 +2356,7 @@ fn nested_structs() {
     let value_1 = value_1.root();
 
     // Tests mapping of different struct type, when `gc -> gc`, `value -> value`
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
     struct(gc) GcStruct(f64, f64);
@@ -2431,7 +2431,7 @@ fn insert_struct() {
     let foo_struct: StructRef = driver.runtime.invoke("foo_new", (a, c)).unwrap();
     let foo_struct = foo_struct.root();
 
-    driver.update(
+    driver.update_file(
         "mod.mun",
         r#"
         struct Bar(i64);
diff --git a/crates/mun_test/src/driver.rs b/crates/mun_test/src/driver.rs
index 9e08073f..fa39ec8c 100644
--- a/crates/mun_test/src/driver.rs
+++ b/crates/mun_test/src/driver.rs
@@ -91,7 +91,7 @@ impl CompileTestDriver {
 
     /// Updates the text of the Mun source and ensures that the generated assembly has been
     /// recompiled.
-    pub fn update(&mut self, path: impl AsRef<mun_paths::RelativePath>, text: &str) {
+    pub fn update_file(&mut self, path: impl AsRef<mun_paths::RelativePath>, text: &str) {
         self.driver.set_file_text(path, text).unwrap();
 
         let compiler_errors = self
@@ -177,8 +177,8 @@ impl CompileAndRunTestDriver {
     /// A reference to the borrowed `runtime` is used as an argument to allow moving of the
     /// existing borrow inside the update function. This obviates the necessity for `update` to use
     /// the `Runtime`.
-    pub fn update(&mut self, path: impl AsRef<mun_paths::RelativePath>, text: &str) {
-        self.driver.update(path, text);
+    pub fn update_file(&mut self, path: impl AsRef<mun_paths::RelativePath>, text: &str) {
+        self.driver.update_file(path, text);
 
         let start_time = Instant::now();