diff --git a/build/plugins/wasmTypes.ts b/build/plugins/wasmTypes.ts
index 73dd6d3..a3097e4 100644
--- a/build/plugins/wasmTypes.ts
+++ b/build/plugins/wasmTypes.ts
@@ -166,12 +166,12 @@ export function renderDts(wasmBytes: Uint8Array, meta?: Map<string, ExportMeta>)
 
     return [
         '// Auto-generated by wasmPlugin. Do not edit.',
-        'declare const _: {',
+        'declare const _: Readonly<{',
         ...fns.map(([name, sig]) => `    ${name}: ${tsSignature(sig, meta?.get(name))};`),
         '    memory: WebAssembly.Memory;',
         '    table: WebAssembly.Table;',
-        '    readonly data: DataView;',
-        '};',
+        '    data: DataView;',
+        '}>;',
         'export default _;',
         '',
     ].join('\n');
diff --git a/build/wasm.d.ts b/build/wasm.d.ts
index 2cef2c1..47f8604 100644
--- a/build/wasm.d.ts
+++ b/build/wasm.d.ts
@@ -2,31 +2,31 @@
 // After a build, a sibling `${file}.d.ts` with concrete export names takes precedence.
 
 declare module '*.cpp' {
-    const _: {
+    const _: Readonly<{
         memory: WebAssembly.Memory;
         table: WebAssembly.Table;
-        readonly data: DataView;
+        data: DataView;
         [fn: string]: unknown;
-    };
+    }>;
     export default _;
 }
 
 declare module '*.c' {
-    const _: {
+    const _: Readonly<{
         memory: WebAssembly.Memory;
         table: WebAssembly.Table;
-        readonly data: DataView;
+        data: DataView;
         [fn: string]: unknown;
-    };
+    }>;
     export default _;
 }
 
 declare module '*.wasm' {
-    const _: {
+    const _: Readonly<{
         memory: WebAssembly.Memory;
         table?: WebAssembly.Table;
         data: DataView;
         [fn: string]: unknown;
-    };
+    }>;
     export default _;
 }
\ No newline at end of file
diff --git a/src/common/physics/engine.c b/src/common/physics/engine.c
index 0961d70..84c2bdf 100644
--- a/src/common/physics/engine.c
+++ b/src/common/physics/engine.c
@@ -6,17 +6,17 @@
 #include <stdlib.h>
 #include <vec2.h>
 
-#define TYPE_EMPTY 0
-#define TYPE_CIRCLE 1
-#define TYPE_PLANE 2
-
-#define rb_get(idx) (rigid_bodies + (idx))
+typedef enum : uint8_t {
+    TYPE_EMPTY = 0,
+    TYPE_CIRCLE = 1,
+    TYPE_PLANE = 2,
+} body_type;
 
 ////////// Types
 
-typedef struct rigid_body_t {
+typedef struct {
     // Public
-    uint8_t type;
+    body_type type;
     uint8_t reserved[3];
     vec2 pos;
     vec2 vel;
@@ -51,6 +51,10 @@ static rigid_body_collision_callback_t rigid_body_collision_callback = NULL;
 
 ////////// Functions
 
+inline static rigid_body* rb_get(rigid_body_index idx) {
+    return (rigid_bodies + (idx));
+}
+
 JS_EXPORT rigid_body* rigid_body_get(rigid_body_index idx) {
     return rb_get(idx);
 }