diff --git a/src/eval.ts b/src/eval.ts
index 29a100b..712d9b2 100644
--- a/src/eval.ts
+++ b/src/eval.ts
@@ -23,7 +23,7 @@ export async function evalModule (code: string, opts: EvaluateOptions = {}): Pro
   })
 }
 
-export function transformModule (code: string, opts: EvaluateOptions): Promise<string> {
+export function transformModule (code: string, opts?: EvaluateOptions): Promise<string> {
   // Convert JSON to module
   if (opts.url && opts.url.endsWith('.json')) {
     return Promise.resolve('export default ' + code)
@@ -37,7 +37,7 @@ export function transformModule (code: string, opts: EvaluateOptions): Promise<s
   return Promise.resolve(code)
 }
 
-export async function resolveImports (code: string, opts: EvaluateOptions): Promise<string> {
+export async function resolveImports (code: string, opts?: EvaluateOptions): Promise<string> {
   const imports = Array.from(code.matchAll(EVAL_ESM_IMPORT_RE)).map(m => m[0])
   if (!imports.length) {
     return code
diff --git a/src/resolve.ts b/src/resolve.ts
index cafbb3b..098ab74 100644
--- a/src/resolve.ts
+++ b/src/resolve.ts
@@ -86,26 +86,26 @@ function _resolve (id: string, opts: ResolveOptions = {}): string {
 /**
  * @deprecated please use `resolve` instead of `resolveSync`
  */
-export function resolveSync (id: string, opts: ResolveOptions): string {
+export function resolveSync (id: string, opts?: ResolveOptions): string {
   return _resolve(id, opts)
 }
 
-export function resolve (id: string, opts: ResolveOptions): Promise<string> {
+export function resolve (id: string, opts?: ResolveOptions): Promise<string> {
   return pcall(resolveSync, id, opts)
 }
 
 /**
  * @deprecated please use `resolvePath` instead of `resolvePathSync`
  */
-export function resolvePathSync (id: string, opts: ResolveOptions) {
+export function resolvePathSync (id: string, opts?: ResolveOptions) {
   return fileURLToPath(resolveSync(id, opts))
 }
 
-export function resolvePath (id: string, opts: ResolveOptions) {
+export function resolvePath (id: string, opts?: ResolveOptions) {
   return pcall(resolvePathSync, id, opts)
 }
 
-export function createResolve (defaults: ResolveOptions) {
+export function createResolve (defaults?: ResolveOptions) {
   return (id, url) => {
     return resolve(id, { url, ...defaults })
   }