diff --git a/docs/api/js-utils.allowedbufferencoding.md b/docs/api/js-utils.allowedbufferencoding.md
index 37802ba..43f5c49 100644
--- a/docs/api/js-utils.allowedbufferencoding.md
+++ b/docs/api/js-utils.allowedbufferencoding.md
@@ -8,5 +8,5 @@
 <b>Signature:</b>
 
 ```typescript
-export declare type AllowedBufferEncoding = 'ascii' | 'utf-8';
+export type AllowedBufferEncoding = 'ascii' | 'utf-8';
 ```
diff --git a/docs/api/js-utils.childspawner.md b/docs/api/js-utils.childspawner.md
index ecfdd57..6870dda 100644
--- a/docs/api/js-utils.childspawner.md
+++ b/docs/api/js-utils.childspawner.md
@@ -8,5 +8,5 @@
 <b>Signature:</b>
 
 ```typescript
-export declare type ChildSpawner = typeof spawn;
+export type ChildSpawner = typeof spawn;
 ```
diff --git a/docs/api/js-utils.maplike.md b/docs/api/js-utils.maplike.md
index 9625db1..2a069e8 100644
--- a/docs/api/js-utils.maplike.md
+++ b/docs/api/js-utils.maplike.md
@@ -9,7 +9,7 @@ A `Map` or dictionary object with string keys and `TVal` values.
 <b>Signature:</b>
 
 ```typescript
-export declare type MapLike<TVal> = Map<string, TVal> | Dict<TVal>;
+export type MapLike<TVal> = Map<string, TVal> | Dict<TVal>;
 ```
 <b>References:</b> [Dict](./js-utils.dict.md)
 
diff --git a/docs/api/js-utils.maybe.md b/docs/api/js-utils.maybe.md
index cc85575..95baa79 100644
--- a/docs/api/js-utils.maybe.md
+++ b/docs/api/js-utils.maybe.md
@@ -9,7 +9,7 @@ Value that may be nil.
 <b>Signature:</b>
 
 ```typescript
-export declare type Maybe<T> = T | None;
+export type Maybe<T> = T | None;
 ```
 <b>References:</b> [None](./js-utils.none.md)
 
diff --git a/docs/api/js-utils.nil.md b/docs/api/js-utils.nil.md
index 8ae386b..e0443ff 100644
--- a/docs/api/js-utils.nil.md
+++ b/docs/api/js-utils.nil.md
@@ -14,7 +14,7 @@ Old name for None.
 <b>Signature:</b>
 
 ```typescript
-export declare type Nil = None;
+export type Nil = None;
 ```
 <b>References:</b> [None](./js-utils.none.md)
 
diff --git a/docs/api/js-utils.none.md b/docs/api/js-utils.none.md
index 7d5efe3..1234441 100644
--- a/docs/api/js-utils.none.md
+++ b/docs/api/js-utils.none.md
@@ -9,5 +9,5 @@ Unset value.
 <b>Signature:</b>
 
 ```typescript
-export declare type None = null | undefined;
+export type None = null | undefined;
 ```
diff --git a/docs/api/js-utils.optional.md b/docs/api/js-utils.optional.md
index 41c1a32..21336a3 100644
--- a/docs/api/js-utils.optional.md
+++ b/docs/api/js-utils.optional.md
@@ -14,7 +14,7 @@ Old name for Maybe.
 <b>Signature:</b>
 
 ```typescript
-export declare type Optional<T> = Maybe<T>;
+export type Optional<T> = Maybe<T>;
 ```
 <b>References:</b> [Maybe](./js-utils.maybe.md)
 
diff --git a/test/utils/TestMap.ts b/test/utils/TestMap.ts
index 36aa61e..65dcf67 100644
--- a/test/utils/TestMap.ts
+++ b/test/utils/TestMap.ts
@@ -46,6 +46,8 @@ describe('map utils', async () => {
 
     over('maps of strings', dictionary(string(), string()), (it) => {
       it('should convert map to dict', async (data) => {
+        delete data.__proto__; // hack for chai, https://github.com/chaijs/chai/issues/518
+
         const map = new Map(Object.entries(data));
         expect(makeDict(map)).to.deep.equal(data);
       });