diff --git a/web3.js/module.d.ts b/web3.js/module.d.ts
index 420fbf74c5..54e8e3b871 100644
--- a/web3.js/module.d.ts
+++ b/web3.js/module.d.ts
@@ -233,73 +233,6 @@ declare module '@solana/web3.js' {
     ): Promise<number>;
   }
 
-  // === src/stake-program.js ===
-  export type StakeAuthorizationType = {
-    index: number;
-  };
-
-  export class Authorized {
-    staker: PublicKey;
-    withdrawer: PublicKey;
-    constructor(staker: PublicKey, withdrawer: PublicKey);
-  }
-
-  export class Lockup {
-    unixTimestamp: number;
-    epoch: number;
-    custodian: PublicKey;
-
-    constructor(unixTimestamp: number, epoch: number, custodian: PublicKey);
-  }
-
-  export class StakeProgram {
-    static programId: PublicKey;
-    static space: number;
-
-    static createAccount(
-      from: PublicKey,
-      stakeAccount: PublicKey,
-      authorized: Authorized,
-      lockup: Lockup,
-      lamports: number,
-    ): Transaction;
-    static createAccountWithSeed(
-      from: PublicKey,
-      stakeAccount: PublicKey,
-      seed: string,
-      authorized: Authorized,
-      lockup: Lockup,
-      lamports: number,
-    ): Transaction;
-    static delegate(
-      stakeAccount: PublicKey,
-      authorizedPubkey: PublicKey,
-      votePubkey: PublicKey,
-    ): Transaction;
-    static authorize(
-      stakeAccount: PublicKey,
-      authorizedPubkey: PublicKey,
-      newAuthorized: PublicKey,
-      stakeAuthorizationType: StakeAuthorizationType,
-    ): Transaction;
-    static split(
-      stakeAccount: PublicKey,
-      authorizedPubkey: PublicKey,
-      lamports: number,
-      splitStakePubkey: PublicKey,
-    ): Transaction;
-    static withdraw(
-      stakeAccount: PublicKey,
-      withdrawerPubkey: PublicKey,
-      to: PublicKey,
-      lamports: number,
-    ): Transaction;
-    static deactivate(
-      stakeAccount: PublicKey,
-      authorizedPubkey: PublicKey,
-    ): Transaction;
-  }
-
   // === src/validator-info.js ===
   export const VALIDATOR_INFO_KEY: PublicKey;
   export type Info = {
@@ -421,6 +354,97 @@ declare module '@solana/web3.js' {
     serialize(): Buffer;
   }
 
+  // === src/stake-program.js ===
+  export type StakeAuthorizationType = {
+    index: number;
+  };
+
+  export class Authorized {
+    staker: PublicKey;
+    withdrawer: PublicKey;
+    constructor(staker: PublicKey, withdrawer: PublicKey);
+  }
+
+  export class Lockup {
+    unixTimestamp: number;
+    epoch: number;
+    custodian: PublicKey;
+
+    constructor(unixTimestamp: number, epoch: number, custodian: PublicKey);
+  }
+
+  export class StakeProgram {
+    static programId: PublicKey;
+    static space: number;
+
+    static createAccount(
+      from: PublicKey,
+      stakeAccount: PublicKey,
+      authorized: Authorized,
+      lockup: Lockup,
+      lamports: number,
+    ): Transaction;
+    static createAccountWithSeed(
+      from: PublicKey,
+      stakeAccount: PublicKey,
+      seed: string,
+      authorized: Authorized,
+      lockup: Lockup,
+      lamports: number,
+    ): Transaction;
+    static delegate(
+      stakeAccount: PublicKey,
+      authorizedPubkey: PublicKey,
+      votePubkey: PublicKey,
+    ): Transaction;
+    static authorize(
+      stakeAccount: PublicKey,
+      authorizedPubkey: PublicKey,
+      newAuthorized: PublicKey,
+      stakeAuthorizationType: StakeAuthorizationType,
+    ): Transaction;
+    static split(
+      stakeAccount: PublicKey,
+      authorizedPubkey: PublicKey,
+      lamports: number,
+      splitStakePubkey: PublicKey,
+    ): Transaction;
+    static withdraw(
+      stakeAccount: PublicKey,
+      withdrawerPubkey: PublicKey,
+      to: PublicKey,
+      lamports: number,
+    ): Transaction;
+    static deactivate(
+      stakeAccount: PublicKey,
+      authorizedPubkey: PublicKey,
+    ): Transaction;
+  }
+
+  export type StakeInstructionType =
+    | 'Initialize'
+    | 'Authorize'
+    | 'Delegate'
+    | 'Split'
+    | 'Withdraw'
+    | 'Deactivate';
+
+  export const STAKE_INSTRUCTION_LAYOUTS: {
+    [StakeInstructionType]: InstructionType;
+  };
+
+  export class StakeInstruction extends TransactionInstruction {
+    type: StakeInstructionType;
+    stakePublicKey: PublicKey | null;
+    authorizedPublicKey: PublicKey | null;
+
+    constructor(
+      opts?: TransactionInstructionCtorFields,
+      type: StakeInstructionType,
+    );
+    static from(instruction: TransactionInstruction): StakeInstruction;
+  }
+
   // === src/system-program.js ===
   export class SystemProgram {
     static programId: PublicKey;
@@ -471,15 +495,29 @@ declare module '@solana/web3.js' {
     ): Transaction;
   }
 
+  export type SystemInstructionType =
+    | 'Create'
+    | 'Assign'
+    | 'Transfer'
+    | 'CreateWithSeed'
+    | 'AdvanceNonceAccount'
+    | 'WithdrawNonceAccount'
+    | 'InitializeNonceAccount'
+    | 'AuthorizeNonceAccount';
+
+  export const SYSTEM_INSTRUCTION_LAYOUTS: {
+    [SystemInstructionType]: InstructionType;
+  };
+
   export class SystemInstruction extends TransactionInstruction {
-    type: InstructionType;
+    type: SystemInstructionType;
     fromPublicKey: PublicKey | null;
     toPublicKey: PublicKey | null;
     amount: number | null;
 
     constructor(
       opts?: TransactionInstructionCtorFields,
-      type?: InstructionType,
+      type: SystemInstructionType,
     );
     static from(instruction: TransactionInstruction): SystemInstruction;
   }
diff --git a/web3.js/module.flow.js b/web3.js/module.flow.js
index 1db334a537..cb2e62f17a 100644
--- a/web3.js/module.flow.js
+++ b/web3.js/module.flow.js
@@ -318,6 +318,30 @@ declare module '@solana/web3.js' {
     ): Transaction;
   }
 
+  declare export type StakeInstructionType =
+    | 'Initialize'
+    | 'Authorize'
+    | 'Delegate'
+    | 'Split'
+    | 'Withdraw'
+    | 'Deactivate';
+
+  declare export var STAKE_INSTRUCTION_LAYOUTS: {
+    [StakeInstructionType]: InstructionType,
+  };
+
+  declare export class StakeInstruction extends TransactionInstruction {
+    type: StakeInstructionType;
+    stakePublicKey: PublicKey | null;
+    authorizedPublicKey: PublicKey | null;
+
+    constructor(
+      opts?: TransactionInstructionCtorFields,
+      type: StakeInstructionType,
+    ): StakeInstruction;
+    static from(instruction: TransactionInstruction): StakeInstruction;
+  }
+
   // === src/system-program.js ===
   declare export class SystemProgram {
     static programId: PublicKey;
@@ -368,15 +392,29 @@ declare module '@solana/web3.js' {
     ): Transaction;
   }
 
+  declare export type SystemInstructionType =
+    | 'Create'
+    | 'Assign'
+    | 'Transfer'
+    | 'CreateWithSeed'
+    | 'AdvanceNonceAccount'
+    | 'WithdrawNonceAccount'
+    | 'InitializeNonceAccount'
+    | 'AuthorizeNonceAccount';
+
+  declare export var SYSTEM_INSTRUCTION_LAYOUTS: {
+    [SystemInstructionType]: InstructionType,
+  };
+
   declare export class SystemInstruction extends TransactionInstruction {
-    type: InstructionType;
+    type: SystemInstructionType;
     fromPublicKey: PublicKey | null;
     toPublicKey: PublicKey | null;
     amount: number | null;
 
     constructor(
       opts?: TransactionInstructionCtorFields,
-      type?: InstructionType,
+      type: SystemInstructionType,
     ): SystemInstruction;
     static from(instruction: TransactionInstruction): SystemInstruction;
   }
diff --git a/web3.js/src/index.js b/web3.js/src/index.js
index 527f15e9d1..4071bdf41a 100644
--- a/web3.js/src/index.js
+++ b/web3.js/src/index.js
@@ -12,7 +12,7 @@ export {
   Lockup,
   StakeAuthorizationLayout,
   StakeInstruction,
-  StakeInstructionLayout,
+  STAKE_INSTRUCTION_LAYOUTS,
   StakeProgram,
 } from './stake-program';
 export {SystemInstruction, SystemProgram} from './system-program';
diff --git a/web3.js/src/stake-program.js b/web3.js/src/stake-program.js
index 52adafc1d3..8cc583fb8a 100644
--- a/web3.js/src/stake-program.js
+++ b/web3.js/src/stake-program.js
@@ -3,7 +3,6 @@
 import * as BufferLayout from 'buffer-layout';
 
 import {encodeData} from './instruction';
-import type {InstructionType} from './instruction';
 import * as Layout from './layout';
 import {PublicKey} from './publickey';
 import {SystemProgram} from './system-program';
@@ -51,12 +50,12 @@ export class Lockup {
  * Stake Instruction class
  */
 export class StakeInstruction extends TransactionInstruction {
-  /**
-   * Type of StakeInstruction
-   */
-  type: InstructionType;
+  _type: StakeInstructionType;
 
-  constructor(opts?: TransactionInstructionCtorFields, type?: InstructionType) {
+  constructor(
+    opts?: TransactionInstructionCtorFields,
+    type: StakeInstructionType,
+  ) {
     if (
       opts &&
       opts.programId &&
@@ -65,9 +64,7 @@ export class StakeInstruction extends TransactionInstruction {
       throw new Error('programId incorrect; not a StakeInstruction');
     }
     super(opts);
-    if (type) {
-      this.type = type;
-    }
+    this._type = type;
   }
 
   static from(instruction: TransactionInstruction): StakeInstruction {
@@ -77,10 +74,11 @@ export class StakeInstruction extends TransactionInstruction {
 
     const instructionTypeLayout = BufferLayout.u32('instruction');
     const typeIndex = instructionTypeLayout.decode(instruction.data);
+
     let type;
-    for (const t in StakeInstructionLayout) {
-      if (StakeInstructionLayout[t].index == typeIndex) {
-        type = StakeInstructionLayout[t];
+    for (const t of Object.keys(STAKE_INSTRUCTION_LAYOUTS)) {
+      if (STAKE_INSTRUCTION_LAYOUTS[t].index == typeIndex) {
+        type = t;
       }
     }
     if (!type) {
@@ -95,12 +93,66 @@ export class StakeInstruction extends TransactionInstruction {
       type,
     );
   }
+
+  /**
+   * Type of StakeInstruction
+   */
+  get type(): StakeInstructionType {
+    return this._type;
+  }
+
+  /**
+   * The `stake account` public key of the instruction;
+   * returns null if StakeInstructionType does not support this field
+   */
+  get stakePublicKey(): PublicKey | null {
+    switch (this.type) {
+      case STAKE_INSTRUCTION_LAYOUTS.Initialize:
+      case STAKE_INSTRUCTION_LAYOUTS.Delegate:
+      case STAKE_INSTRUCTION_LAYOUTS.Authorize:
+      case STAKE_INSTRUCTION_LAYOUTS.Split:
+      case STAKE_INSTRUCTION_LAYOUTS.Withdraw:
+      case STAKE_INSTRUCTION_LAYOUTS.Deactivate:
+        return this.keys[0].pubkey;
+      default:
+        return null;
+    }
+  }
+
+  /**
+   * The `authorized account` public key of the instruction;
+   *
+   * returns null if StakeInstructionType does not support this field
+   */
+  get authorizedPublicKey(): PublicKey | null {
+    switch (this.type) {
+      case STAKE_INSTRUCTION_LAYOUTS.Delegate:
+        return this.keys[5].pubkey;
+      case STAKE_INSTRUCTION_LAYOUTS.Authorize:
+        return this.keys[2].pubkey;
+      case STAKE_INSTRUCTION_LAYOUTS.Split:
+        return this.keys[2].pubkey;
+      case STAKE_INSTRUCTION_LAYOUTS.Withdraw:
+        return this.keys[4].pubkey;
+      case STAKE_INSTRUCTION_LAYOUTS.Deactivate:
+        return this.keys[0].pubkey;
+      default:
+        return null;
+    }
+  }
 }
 
 /**
- * An enumeration of valid StakeInstructionTypes
+ * An enumeration of valid StakeInstructionType's
+ * @typedef { 'Initialize' | 'Authorize' | 'Delegate' | 'Split' | 'Withdraw'
+ | 'Deactivate' } StakeInstructionType
  */
-export const StakeInstructionLayout = Object.freeze({
+export type StakeInstructionType = $Keys<typeof STAKE_INSTRUCTION_LAYOUTS>;
+
+/**
+ * An enumeration of valid stake InstructionType's
+ */
+export const STAKE_INSTRUCTION_LAYOUTS = Object.freeze({
   Initialize: {
     index: 0,
     layout: BufferLayout.struct([
@@ -117,7 +169,7 @@ export const StakeInstructionLayout = Object.freeze({
       BufferLayout.u32('stakeAuthorizationType'),
     ]),
   },
-  DelegateStake: {
+  Delegate: {
     index: 2,
     layout: BufferLayout.struct([BufferLayout.u32('instruction')]),
   },
@@ -150,7 +202,7 @@ export type StakeAuthorizationType = {|
 |};
 
 /**
- * An enumeration of valid StakeInstructionTypes
+ * An enumeration of valid StakeAuthorizationLayout's
  */
 export const StakeAuthorizationLayout = Object.freeze({
   Staker: {
@@ -183,11 +235,11 @@ export class StakeProgram {
    * Generate an Initialize instruction to add to a Stake Create transaction
    */
   static initialize(
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     authorized: Authorized,
     lockup: Lockup,
   ): TransactionInstruction {
-    const type = StakeInstructionLayout.Initialize;
+    const type = STAKE_INSTRUCTION_LAYOUTS.Initialize;
     const data = encodeData(type, {
       authorized: {
         staker: authorized.staker.toBuffer(),
@@ -201,7 +253,7 @@ export class StakeProgram {
     });
     const instructionData = {
       keys: [
-        {pubkey: stakeAccount, isSigner: false, isWritable: true},
+        {pubkey: stakePubkey, isSigner: false, isWritable: true},
         {pubkey: SYSVAR_RENT_PUBKEY, isSigner: false, isWritable: false},
       ],
       programId: this.programId,
@@ -216,7 +268,7 @@ export class StakeProgram {
    */
   static createAccountWithSeed(
     from: PublicKey,
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     base: PublicKey,
     seed: string,
     authorized: Authorized,
@@ -225,7 +277,7 @@ export class StakeProgram {
   ): Transaction {
     let transaction = SystemProgram.createAccountWithSeed(
       from,
-      stakeAccount,
+      stakePubkey,
       base,
       seed,
       lamports,
@@ -233,7 +285,7 @@ export class StakeProgram {
       this.programId,
     );
 
-    return transaction.add(this.initialize(stakeAccount, authorized, lockup));
+    return transaction.add(this.initialize(stakePubkey, authorized, lockup));
   }
 
   /**
@@ -241,20 +293,20 @@ export class StakeProgram {
    */
   static createAccount(
     from: PublicKey,
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     authorized: Authorized,
     lockup: Lockup,
     lamports: number,
   ): Transaction {
     let transaction = SystemProgram.createAccount(
       from,
-      stakeAccount,
+      stakePubkey,
       lamports,
       this.space,
       this.programId,
     );
 
-    return transaction.add(this.initialize(stakeAccount, authorized, lockup));
+    return transaction.add(this.initialize(stakePubkey, authorized, lockup));
   }
 
   /**
@@ -263,16 +315,16 @@ export class StakeProgram {
    * to a new validator Vote PublicKey.
    */
   static delegate(
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     authorizedPubkey: PublicKey,
     votePubkey: PublicKey,
   ): Transaction {
-    const type = StakeInstructionLayout.DelegateStake;
+    const type = STAKE_INSTRUCTION_LAYOUTS.Delegate;
     const data = encodeData(type);
 
     return new Transaction().add({
       keys: [
-        {pubkey: stakeAccount, isSigner: false, isWritable: true},
+        {pubkey: stakePubkey, isSigner: false, isWritable: true},
         {pubkey: votePubkey, isSigner: false, isWritable: false},
         {pubkey: SYSVAR_CLOCK_PUBKEY, isSigner: false, isWritable: false},
         {
@@ -293,12 +345,12 @@ export class StakeProgram {
    * or Withdrawer on the Stake account.
    */
   static authorize(
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     authorizedPubkey: PublicKey,
     newAuthorized: PublicKey,
     stakeAuthorizationType: StakeAuthorizationType,
   ): Transaction {
-    const type = StakeInstructionLayout.Authorize;
+    const type = STAKE_INSTRUCTION_LAYOUTS.Authorize;
     const data = encodeData(type, {
       newAuthorized: newAuthorized.toBuffer(),
       stakeAuthorizationType: stakeAuthorizationType.index,
@@ -306,7 +358,7 @@ export class StakeProgram {
 
     return new Transaction().add({
       keys: [
-        {pubkey: stakeAccount, isSigner: false, isWritable: true},
+        {pubkey: stakePubkey, isSigner: false, isWritable: true},
         {pubkey: SYSVAR_CLOCK_PUBKEY, isSigner: false, isWritable: true},
         {pubkey: authorizedPubkey, isSigner: true, isWritable: false},
       ],
@@ -319,25 +371,25 @@ export class StakeProgram {
    * Generate a Transaction that splits Stake tokens into another stake account
    */
   static split(
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     authorizedPubkey: PublicKey,
     lamports: number,
     splitStakePubkey: PublicKey,
   ): Transaction {
     let transaction = SystemProgram.createAccount(
-      stakeAccount,
+      stakePubkey,
       splitStakePubkey,
       0,
       this.space,
       this.programId,
     );
     transaction.instructions[0].keys[0].isSigner = false;
-    const type = StakeInstructionLayout.Split;
+    const type = STAKE_INSTRUCTION_LAYOUTS.Split;
     const data = encodeData(type, {lamports});
 
     return transaction.add({
       keys: [
-        {pubkey: stakeAccount, isSigner: false, isWritable: true},
+        {pubkey: stakePubkey, isSigner: false, isWritable: true},
         {pubkey: splitStakePubkey, isSigner: false, isWritable: true},
         {pubkey: authorizedPubkey, isSigner: true, isWritable: false},
       ],
@@ -350,17 +402,17 @@ export class StakeProgram {
    * Generate a Transaction that withdraws deactivated Stake tokens.
    */
   static withdraw(
-    stakeAccount: PublicKey,
-    withdrawerPubkey: PublicKey,
+    stakePubkey: PublicKey,
+    authorizedPubkey: PublicKey,
     to: PublicKey,
     lamports: number,
   ): Transaction {
-    const type = StakeInstructionLayout.Withdraw;
+    const type = STAKE_INSTRUCTION_LAYOUTS.Withdraw;
     const data = encodeData(type, {lamports});
 
     return new Transaction().add({
       keys: [
-        {pubkey: stakeAccount, isSigner: false, isWritable: true},
+        {pubkey: stakePubkey, isSigner: false, isWritable: true},
         {pubkey: to, isSigner: false, isWritable: true},
         {pubkey: SYSVAR_CLOCK_PUBKEY, isSigner: false, isWritable: false},
         {
@@ -368,7 +420,7 @@ export class StakeProgram {
           isSigner: false,
           isWritable: false,
         },
-        {pubkey: withdrawerPubkey, isSigner: true, isWritable: false},
+        {pubkey: authorizedPubkey, isSigner: true, isWritable: false},
       ],
       programId: this.programId,
       data,
@@ -379,15 +431,15 @@ export class StakeProgram {
    * Generate a Transaction that deactivates Stake tokens.
    */
   static deactivate(
-    stakeAccount: PublicKey,
+    stakePubkey: PublicKey,
     authorizedPubkey: PublicKey,
   ): Transaction {
-    const type = StakeInstructionLayout.Deactivate;
+    const type = STAKE_INSTRUCTION_LAYOUTS.Deactivate;
     const data = encodeData(type);
 
     return new Transaction().add({
       keys: [
-        {pubkey: stakeAccount, isSigner: false, isWritable: true},
+        {pubkey: stakePubkey, isSigner: false, isWritable: true},
         {pubkey: SYSVAR_CLOCK_PUBKEY, isSigner: false, isWritable: false},
         {pubkey: authorizedPubkey, isSigner: true, isWritable: false},
       ],
diff --git a/web3.js/src/system-program.js b/web3.js/src/system-program.js
index 9e9f1a5b02..11ca4f03f5 100644
--- a/web3.js/src/system-program.js
+++ b/web3.js/src/system-program.js
@@ -3,7 +3,6 @@
 import * as BufferLayout from 'buffer-layout';
 
 import {encodeData} from './instruction';
-import type {InstructionType} from './instruction';
 import * as Layout from './layout';
 import {PublicKey} from './publickey';
 import {SYSVAR_RECENT_BLOCKHASHES_PUBKEY, SYSVAR_RENT_PUBKEY} from './sysvar';
@@ -17,9 +16,12 @@ export class SystemInstruction extends TransactionInstruction {
   /**
    * Type of SystemInstruction
    */
-  type: InstructionType;
+  _type: SystemInstructionType;
 
-  constructor(opts?: TransactionInstructionCtorFields, type?: InstructionType) {
+  constructor(
+    opts?: TransactionInstructionCtorFields,
+    type: SystemInstructionType,
+  ) {
     if (
       opts &&
       opts.programId &&
@@ -28,9 +30,7 @@ export class SystemInstruction extends TransactionInstruction {
       throw new Error('programId incorrect; not a SystemInstruction');
     }
     super(opts);
-    if (type) {
-      this.type = type;
-    }
+    this._type = type;
   }
 
   static from(instruction: TransactionInstruction): SystemInstruction {
@@ -41,9 +41,9 @@ export class SystemInstruction extends TransactionInstruction {
     const instructionTypeLayout = BufferLayout.u32('instruction');
     const typeIndex = instructionTypeLayout.decode(instruction.data);
     let type;
-    for (const t in SystemInstructionLayout) {
-      if (SystemInstructionLayout[t].index == typeIndex) {
-        type = SystemInstructionLayout[t];
+    for (const t of Object.keys(SYSTEM_INSTRUCTION_LAYOUTS)) {
+      if (SYSTEM_INSTRUCTION_LAYOUTS[t].index == typeIndex) {
+        type = t;
       }
     }
     if (!type) {
@@ -59,20 +59,27 @@ export class SystemInstruction extends TransactionInstruction {
     );
   }
 
+  /**
+   * Type of SystemInstruction
+   */
+  get type(): SystemInstructionType {
+    return this._type;
+  }
+
   /**
    * The `from` public key of the instruction;
    * returns null if SystemInstructionType does not support this field
    */
   get fromPublicKey(): PublicKey | null {
-    if (
-      this.type == SystemInstructionLayout.Create ||
-      this.type == SystemInstructionLayout.CreateWithSeed ||
-      this.type == SystemInstructionLayout.WithdrawNonceAccount ||
-      this.type == SystemInstructionLayout.Transfer
-    ) {
-      return this.keys[0].pubkey;
+    switch (this.type) {
+      case 'Create':
+      case 'CreateWithSeed':
+      case 'WithdrawNonceAccount':
+      case 'Transfer':
+        return this.keys[0].pubkey;
+      default:
+        return null;
     }
-    return null;
   }
 
   /**
@@ -80,15 +87,15 @@ export class SystemInstruction extends TransactionInstruction {
    * returns null if SystemInstructionType does not support this field
    */
   get toPublicKey(): PublicKey | null {
-    if (
-      this.type == SystemInstructionLayout.Create ||
-      this.type == SystemInstructionLayout.CreateWithSeed ||
-      this.type == SystemInstructionLayout.WithdrawNonceAccount ||
-      this.type == SystemInstructionLayout.Transfer
-    ) {
-      return this.keys[1].pubkey;
+    switch (this.type) {
+      case 'Create':
+      case 'CreateWithSeed':
+      case 'WithdrawNonceAccount':
+      case 'Transfer':
+        return this.keys[1].pubkey;
+      default:
+        return null;
     }
-    return null;
   }
 
   /**
@@ -96,23 +103,31 @@ export class SystemInstruction extends TransactionInstruction {
    * returns null if SystemInstructionType does not support this field
    */
   get amount(): number | null {
-    const data = this.type.layout.decode(this.data);
-    if (
-      this.type == SystemInstructionLayout.Create ||
-      this.type == SystemInstructionLayout.CreateWithSeed ||
-      this.type == SystemInstructionLayout.WithdrawNonceAccount ||
-      this.type == SystemInstructionLayout.Transfer
-    ) {
-      return data.lamports;
+    const data = SYSTEM_INSTRUCTION_LAYOUTS[this.type].layout.decode(this.data);
+    switch (this.type) {
+      case 'Create':
+      case 'CreateWithSeed':
+      case 'WithdrawNonceAccount':
+      case 'Transfer':
+        return data.lamports;
+      default:
+        return null;
     }
-    return null;
   }
 }
 
 /**
- * An enumeration of valid SystemInstructionTypes
+ * An enumeration of valid SystemInstructionType's
+ * @typedef {'Create' | 'Assign' | 'Transfer' | 'CreateWithSeed'
+ | 'AdvanceNonceAccount' | 'WithdrawNonceAccount' | 'InitializeNonceAccount'
+ | 'AuthorizeNonceAccount'} SystemInstructionType
  */
-const SystemInstructionLayout = Object.freeze({
+export type SystemInstructionType = $Keys<typeof SYSTEM_INSTRUCTION_LAYOUTS>;
+
+/**
+ * An enumeration of valid system InstructionType's
+ */
+const SYSTEM_INSTRUCTION_LAYOUTS = Object.freeze({
   Create: {
     index: 0,
     layout: BufferLayout.struct([
@@ -204,7 +219,7 @@ export class SystemProgram {
     space: number,
     programId: PublicKey,
   ): Transaction {
-    const type = SystemInstructionLayout.Create;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.Create;
     const data = encodeData(type, {
       lamports,
       space,
@@ -229,7 +244,7 @@ export class SystemProgram {
     to: PublicKey,
     lamports: number,
   ): Transaction {
-    const type = SystemInstructionLayout.Transfer;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.Transfer;
     const data = encodeData(type, {lamports});
 
     return new Transaction().add({
@@ -246,7 +261,7 @@ export class SystemProgram {
    * Generate a Transaction that assigns an account to a program
    */
   static assign(from: PublicKey, programId: PublicKey): Transaction {
-    const type = SystemInstructionLayout.Assign;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.Assign;
     const data = encodeData(type, {programId: programId.toBuffer()});
 
     return new Transaction().add({
@@ -269,7 +284,7 @@ export class SystemProgram {
     space: number,
     programId: PublicKey,
   ): Transaction {
-    const type = SystemInstructionLayout.CreateWithSeed;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.CreateWithSeed;
     const data = encodeData(type, {
       base: base.toBuffer(),
       seed,
@@ -305,7 +320,7 @@ export class SystemProgram {
       this.programId,
     );
 
-    const type = SystemInstructionLayout.InitializeNonceAccount;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.InitializeNonceAccount;
     const data = encodeData(type, {
       authorized: authorizedPubkey.toBuffer(),
     });
@@ -332,7 +347,7 @@ export class SystemProgram {
     nonceAccount: PublicKey,
     authorizedPubkey: PublicKey,
   ): TransactionInstruction {
-    const type = SystemInstructionLayout.AdvanceNonceAccount;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.AdvanceNonceAccount;
     const data = encodeData(type);
     const instructionData = {
       keys: [
@@ -359,7 +374,7 @@ export class SystemProgram {
     to: PublicKey,
     lamports: number,
   ): Transaction {
-    const type = SystemInstructionLayout.WithdrawNonceAccount;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.WithdrawNonceAccount;
     const data = encodeData(type, {lamports});
 
     return new Transaction().add({
@@ -392,7 +407,7 @@ export class SystemProgram {
     authorizedPubkey: PublicKey,
     newAuthorized: PublicKey,
   ): Transaction {
-    const type = SystemInstructionLayout.AuthorizeNonceAccount;
+    const type = SYSTEM_INSTRUCTION_LAYOUTS.AuthorizeNonceAccount;
     const data = encodeData(type, {
       newAuthorized: newAuthorized.toBuffer(),
     });
diff --git a/web3.js/test/stake-program.test.js b/web3.js/test/stake-program.test.js
index 39ce2e8978..2bd65df5ed 100644
--- a/web3.js/test/stake-program.test.js
+++ b/web3.js/test/stake-program.test.js
@@ -10,7 +10,6 @@ import {
   LAMPORTS_PER_SOL,
   StakeAuthorizationLayout,
   StakeInstruction,
-  StakeInstructionLayout,
   StakeProgram,
   SystemInstruction,
   SystemProgram,
@@ -197,7 +196,7 @@ test('StakeInstructions', () => {
   const stakeInstruction = StakeInstruction.from(
     createWithSeedTransaction.instructions[1],
   );
-  expect(stakeInstruction.type).toEqual(StakeInstructionLayout.Initialize);
+  expect(stakeInstruction.type).toEqual('Initialize');
 
   expect(() => {
     StakeInstruction.from(createWithSeedTransaction.instructions[0]);
@@ -216,9 +215,7 @@ test('StakeInstructions', () => {
   const anotherStakeInstruction = StakeInstruction.from(
     delegateTransaction.instructions[0],
   );
-  expect(anotherStakeInstruction.type).toEqual(
-    StakeInstructionLayout.DelegateStake,
-  );
+  expect(anotherStakeInstruction.type).toEqual('Delegate');
 });
 
 test('live staking actions', async () => {
diff --git a/web3.js/test/system-program.test.js b/web3.js/test/system-program.test.js
index c1bd8c7183..b5006e74cb 100644
--- a/web3.js/test/system-program.test.js
+++ b/web3.js/test/system-program.test.js
@@ -249,7 +249,7 @@ test('non-SystemInstruction error', () => {
     data: Buffer.from([2, 0, 0, 0]),
   };
   expect(() => {
-    new SystemInstruction(badProgramId);
+    new SystemInstruction(badProgramId, 'Create');
   }).toThrow();
 
   const amount = 123;