diff --git a/tests/setup.ts b/tests/setup.ts
index 2654285..2deaf45 100644
--- a/tests/setup.ts
+++ b/tests/setup.ts
@@ -75,8 +75,8 @@ declare module "bun:test" {
 }
 
 expect.extend({
-  async toEqualValue(received: string | any[] | Bytecode, expected: any) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toEqualValue(this: void, received: unknown, expected: any) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const expectedValue = toValue(expected)
     const pass = isEqual(result, expectedValue)
@@ -90,8 +90,8 @@ expect.extend({
     }
   },
 
-  async toBeNull(received: string | any[] | Bytecode) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeNull(this: void, received: unknown) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const pass = result.type === "null"
 
@@ -104,8 +104,8 @@ expect.extend({
     }
   },
 
-  async toBeBoolean(received: string | any[] | Bytecode, expected: boolean) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeBoolean(this: void, received: unknown, expected: boolean) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const pass = result.type === "boolean" && result.value === expected
 
@@ -118,8 +118,8 @@ expect.extend({
     }
   },
 
-  async toBeNumber(received: string | any[] | Bytecode, expected: number) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeNumber(this: void, received: unknown, expected: number) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const pass = result.type === "number" && result.value === expected
 
@@ -132,8 +132,8 @@ expect.extend({
     }
   },
 
-  async toBeString(received: string | any[] | Bytecode, expected: string) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeString(this: void, received: unknown, expected: string) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const pass = result.type === "string" && result.value === expected
 
@@ -146,8 +146,8 @@ expect.extend({
     }
   },
 
-  async toBeArray(received: string | any[] | Bytecode, expected: any[]) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeArray(this: void, received: unknown, expected: any[]) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const expectedValue = toValue(expected)
     const pass = result.type === "array" && isEqual(result, expectedValue)
@@ -161,8 +161,8 @@ expect.extend({
     }
   },
 
-  async toBeDict(received: string | any[] | Bytecode, expected: Record<string, any>) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeDict(this: void, received: unknown, expected: Record<string, any>) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const expectedValue = toValue(expected)
     const pass = result.type === "dict" && isEqual(result, expectedValue)
@@ -176,8 +176,8 @@ expect.extend({
     }
   },
 
-  async toBeFunction(received: string | any[] | Bytecode) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeFunction(this: void, received: unknown) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     const pass = result.type === "function" || result.type === "native"
 
@@ -190,8 +190,8 @@ expect.extend({
     }
   },
 
-  async toBeTruthy(received: string | any[] | Bytecode) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeTruthy(this: void, received: unknown) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     // ReefVM semantics: only null and false are falsy
     const pass = !(result.type === "null" || (result.type === "boolean" && !result.value))
@@ -205,8 +205,8 @@ expect.extend({
     }
   },
 
-  async toBeFalsy(received: string | any[] | Bytecode) {
-    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received) : received
+  async toBeFalsy(this: void, received: unknown) {
+    const bytecode = typeof received === "string" || Array.isArray(received) ? toBytecode(received as string | any[]) : received as Bytecode
     const result = await run(bytecode)
     // ReefVM semantics: only null and false are falsy
     const pass = result.type === "null" || (result.type === "boolean" && !result.value)