diff --git a/src/ts/0x.js.ts b/src/ts/0x.js.ts
index 893d95de62..ba922d3dbb 100644
--- a/src/ts/0x.js.ts
+++ b/src/ts/0x.js.ts
@@ -132,8 +132,9 @@ export class ZeroEx {
 
     /**
      * Converts BigNumber instance to BN
-     * We do it because ethABI accepts only BN's
-     * We should be consistent about using BigNumbers in our codebase and not use BN anywhere else
+     * The only we convert to BN is to remain compatible with `ethABI. soliditySHA3 ` that
+     * expects values of Solidity type `uint` to be of type `BN`.
+     * We do not use BN anywhere else in the codebase.
      */
     private static bigNumberToBN(value: BigNumber.BigNumber) {
         return new BN(value.toString(), 10);
diff --git a/src/ts/globals.d.ts b/src/ts/globals.d.ts
index a50c635fb4..99baf593f8 100644
--- a/src/ts/globals.d.ts
+++ b/src/ts/globals.d.ts
@@ -26,5 +26,5 @@ declare module 'ethereumjs-util' {
 }
 
 declare module 'ethereumjs-abi' {
-    const soliditySHA3: (argTypes: string[], args: any) => Buffer;
+    const soliditySHA3: (argTypes: string[], args: any[]) => Buffer;
 }
diff --git a/src/ts/types.ts b/src/ts/types.ts
index c49ef2331e..04902cca63 100644
--- a/src/ts/types.ts
+++ b/src/ts/types.ts
@@ -13,8 +13,5 @@ function strEnum(values: string[]): {[key: string]: string} {
 export const SolidityTypes = strEnum([
     'address',
     'uint256',
-    'uint8',
-    'string',
-    'bool',
 ]);
 export type SolidityTypes = keyof typeof SolidityTypes;