diff --git a/package.json b/package.json
index dc67342d8..524757eec 100644
--- a/package.json
+++ b/package.json
@@ -88,7 +88,7 @@
     "jsdom": "^19.0.0",
     "prettier": "^2.1.2",
     "ts-jest": "^29.0.0",
-    "typescript": "^4.0.3"
+    "typescript": "^5.4.5"
   },
   "jest": {
     "snapshotFormat": {
diff --git a/src/infiniteLoops/__tests__/instrument.ts b/src/infiniteLoops/__tests__/instrument.ts
index 56886b86a..8244c07b7 100644
--- a/src/infiniteLoops/__tests__/instrument.ts
+++ b/src/infiniteLoops/__tests__/instrument.ts
@@ -12,7 +12,7 @@ import {
 
 function mockFunctionsAndState() {
   const theState = undefined
-  const functions = {}
+  const functions: Partial<Record<functionNames, any>> = {}
   const returnFirst = (...args: any[]) => args[0]
   const nothing = (..._args: any[]) => {}
   functions[functionNames.nothingFunction] = nothing
diff --git a/src/infiniteLoops/instrument.ts b/src/infiniteLoops/instrument.ts
index acd6c7354..7b5846f2d 100644
--- a/src/infiniteLoops/instrument.ts
+++ b/src/infiniteLoops/instrument.ts
@@ -4,8 +4,9 @@ import type es from 'estree'
 import { transformImportDeclarations } from '../transpiler/transpiler'
 import type { Node } from '../types'
 import * as create from '../utils/ast/astCreator'
-import { recursive, simple, WalkerCallback } from '../utils/walkers'
 import { getIdsFromDeclaration } from '../utils/ast/helpers'
+import { objectValues } from '../utils/misc'
+import { recursive, simple, WalkerCallback } from '../utils/walkers'
 // transforms AST of program
 
 const globalIds = {
@@ -40,8 +41,8 @@ enum FunctionNames {
  * E.g. "function f(f)..." -> "function f_0(f_1)..."
  * @param predefined A table of [key: string, value:string], where variables named 'key' will be renamed to 'value'
  */
-function unshadowVariables(program: Node, predefined = {}) {
-  for (const name of Object.values(globalIds)) {
+function unshadowVariables(program: Node, predefined: Record<string, string> = {}) {
+  for (const name of objectValues(globalIds)) {
     predefined[name] = name
   }
   const seenIds = new Set()
@@ -607,7 +608,7 @@ function instrument(
   builtins: Iterable<string>
 ): string {
   const { builtinsId, functionsId, stateId } = globalIds
-  const predefined = {}
+  const predefined: Record<string, string> = {}
   predefined[builtinsId] = builtinsId
   predefined[functionsId] = functionsId
   predefined[stateId] = stateId
@@ -640,7 +641,7 @@ function instrument(
 }
 
 export {
-  instrument,
   FunctionNames as InfiniteLoopRuntimeFunctions,
-  globalIds as InfiniteLoopRuntimeObjectNames
+  globalIds as InfiniteLoopRuntimeObjectNames,
+  instrument
 }
diff --git a/src/interpreter/interpreter.ts b/src/interpreter/interpreter.ts
index 2af008d68..97aa9f525 100644
--- a/src/interpreter/interpreter.ts
+++ b/src/interpreter/interpreter.ts
@@ -10,12 +10,12 @@ import * as errors from '../errors/errors'
 import { RuntimeSourceError } from '../errors/runtimeSourceError'
 import { checkEditorBreakpoints } from '../stdlib/inspector'
 import {
+  Variant,
   type Context,
   type ContiguousArrayElements,
   type Environment,
   type Node,
-  type Value,
-  Variant
+  type Value
 } from '../types'
 import * as create from '../utils/ast/astCreator'
 import { conditionalExpression, literal, primitive } from '../utils/ast/astCreator'
@@ -637,7 +637,7 @@ export const evaluators: { [nodeType: string]: Evaluator<Node> } = {
   },
 
   ObjectExpression: function*(node: es.ObjectExpression, context: Context) {
-    const obj = {}
+    const obj: Record<any, any> = {}
     for (const propUntyped of node.properties) {
       // node.properties: es.Property | es.SpreadExpression, but
       // our Acorn is set to ES6 which cannot have a es.SpreadExpression
diff --git a/src/parser/__tests__/disallowed-syntax.ts b/src/parser/__tests__/disallowed-syntax.ts
index 5f6487027..6acf224f4 100644
--- a/src/parser/__tests__/disallowed-syntax.ts
+++ b/src/parser/__tests__/disallowed-syntax.ts
@@ -412,7 +412,7 @@ test('Cannot use function expressions', () => {
     stripIndent`
     (function fib(x) { return x <= 1 ? x : fib(x-1) + fib(x-2); })(4);
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`"Line 1: Function expressions are not allowed"`)
 })
 
@@ -422,7 +422,7 @@ test('Cannot use function expressions - verbose', () => {
     "enable verbose";
     (function fib(x) { return x <= 1 ? x : fib(x-1) + fib(x-2); })(4);
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`
             "Line 2, Column 1: Function expressions are not allowed
             You are trying to use Function expressions, which is not allowed (yet).
@@ -435,7 +435,7 @@ test('Cannot use function expressions', () => {
     stripIndent`
     (function(x) { return x + 1; })(4);
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`"Line 1: Function expressions are not allowed"`)
 })
 
@@ -445,7 +445,7 @@ test('Cannot use function expressions - verbose', () => {
     "enable verbose";
     (function(x) { return x + 1; })(4);
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`
             "Line 2, Column 1: Function expressions are not allowed
             You are trying to use Function expressions, which is not allowed (yet).
@@ -840,7 +840,7 @@ test('no classes', () => {
     class Box {
     }
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`
             "Line 1: Class bodys are not allowed
             Line 1: Class declarations are not allowed"
@@ -854,7 +854,7 @@ test('no classes - verbose', () => {
     class Box {
     }
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`
             "Line 2, Column 10: Class bodys are not allowed
             You are trying to use Class bodys, which is not allowed (yet).
@@ -874,7 +874,7 @@ test('no super', () => {
       }
     }
     `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`
             "Line 3: Supers are not allowed
             Line 2: Function expressions are not allowed
@@ -894,7 +894,7 @@ test('no super - verbose', () => {
       }
     }
   `,
-    { chapter: 5 }
+    { chapter: 5 as Chapter }
   ).toMatchInlineSnapshot(`
             "Line 4, Column 4: Supers are not allowed
             You are trying to use Supers, which is not allowed (yet).
diff --git a/src/stepper/converter.ts b/src/stepper/converter.ts
index f0f508802..927f3f7e7 100644
--- a/src/stepper/converter.ts
+++ b/src/stepper/converter.ts
@@ -53,7 +53,7 @@ export function nodeToValue(node: substituterNodes): any {
   return node.type === 'Literal'
     ? node.value
     : util.isBuiltinFunction(node)
-    ? builtin[(node as es.Identifier).name]
+    ? builtin[(node as es.Identifier).name as keyof typeof builtin]
     : // tslint:disable-next-line
       eval(javascriptify(node))
 }
@@ -62,7 +62,7 @@ export function nodeToValueWithContext(node: substituterNodes, context: Context)
   return node.type === 'Literal'
     ? node.value
     : util.isBuiltinFunction(node)
-    ? builtin[(node as es.Identifier).name]
+    ? builtin[(node as es.Identifier).name as keyof typeof builtin]
     : node.type === 'Identifier' && util.isImportedFunction(node, context)
     ? context.runtime.environments[0].head[node.name]
     : // tslint:disable-next-line
@@ -77,11 +77,13 @@ function evaluateFunctionObject(node: substituterNodes, context: Context) {
     }
     visited.add(node)
     if (node.type === 'Identifier' && builtinFunctions[node.name]) {
+      // @ts-expect-error implicitAnyIndexError
       global[node.name] = builtinFunctions[node.name]
     }
-    for (const key in node) {
+    for (const k in node) {
+      const key = k as keyof typeof node
       if (node[key] && typeof node[key] === 'object') {
-        lookUpIdentifiers(node[key], visited)
+        lookUpIdentifiers(node[key] as any, visited)
       }
     }
   }
diff --git a/src/stepper/stepper.ts b/src/stepper/stepper.ts
index 23be27b58..8f95d63bb 100644
--- a/src/stepper/stepper.ts
+++ b/src/stepper/stepper.ts
@@ -22,6 +22,7 @@ import {
   dummyVariableDeclarator
 } from '../utils/ast/dummyAstCreator'
 import { filterImportDeclarations } from '../utils/ast/helpers'
+import { objectGetOwnPropertyNames } from '../utils/misc'
 import { evaluateBinaryExpression, evaluateUnaryExpression } from '../utils/operators'
 import * as rttc from '../utils/rttc'
 import { checkProgramForUndefinedVariables } from '../validator/validator'
@@ -210,7 +211,7 @@ function findMain(
 
   const freeNames: any[] = []
 
-  const finders = {
+  const finders: Partial<Record<any, (target: any) => void>> = {
     Identifier(target: es.Identifier): void {
       seenBefore.set(target, target)
       let bound = false
@@ -418,7 +419,7 @@ function substituteMain(
    *    and push the appropriate access string into the path
    * 3. Return the dummyReplacement
    */
-  const substituters = {
+  const substituters: Partial<Record<substituterNodes['type'], any>> = {
     // if name to be replaced is found,
     // push endMarker into path
     Identifier(
@@ -1325,7 +1326,7 @@ function reduceMain(
 
   // converts body of code to string
   function bodify(target: substituterNodes): string {
-    const bodifiers = {
+    const bodifiers: Partial<Record<substituterNodes['type'], (target: any) => string>> = {
       Literal: (target: es.Literal): string =>
         target.raw !== undefined ? target.raw : String(target.value),
 
@@ -1409,7 +1410,7 @@ function reduceMain(
 
   // generates string to explain current step
   function explain(target: substituterNodes): string {
-    const explainers = {
+    const explainers: Partial<Record<substituterNodes['type'], (target: any) => string>> = {
       BinaryExpression: (target: es.BinaryExpression): string =>
         'Binary expression ' + bodify(target) + ' evaluated',
 
@@ -1496,7 +1497,7 @@ function reduceMain(
     return explainer === undefined ? '...' : explainer(target)
   }
 
-  const reducers = {
+  const reducers: Partial<Record<substituterNodes['type'], any>> = {
     // source 0
     Identifier(
       node: es.Identifier,
@@ -1738,8 +1739,10 @@ function reduceMain(
           paths,
           explain(node)
         ]
+        // @ts-expect-error implicitAnyIndexError
       } else if (typeof builtin[(callee as es.Identifier).name] === 'function') {
         // Source specific built-in function
+        // @ts-expect-error implicitAnyIndexError
         return [builtin[(callee as es.Identifier).name](...args), context, paths, explain(node)]
       } else {
         // Common built-in function
@@ -1825,10 +1828,12 @@ function reduceMain(
             )
 
             // Fix path highlighting after preserving first statement
-            path.forEach(pathStep => {
+            path.forEach((pathStep: any[]) => {
               pathStep.forEach((_, i) => {
                 if (i == 0) {
-                  pathStep[i] = pathStep[i].replace(/\d+/g, match => String(Number(match) + 1))
+                  pathStep[i] = pathStep[i].replace(/\d+/g, (match: any) =>
+                    String(Number(match) + 1)
+                  )
                 }
               })
             })
@@ -2050,10 +2055,12 @@ function reduceMain(
             )
 
             // Fix path highlighting after preserving first statement
-            path.forEach(pathStep => {
+            path.forEach((pathStep: any[]) => {
               pathStep.forEach((_, i) => {
                 if (i == 0) {
-                  pathStep[i] = pathStep[i].replace(/\d+/g, match => String(Number(match) + 1))
+                  pathStep[i] = pathStep[i].replace(/\d+/g, (match: any) =>
+                    String(Number(match) + 1)
+                  )
                 }
               })
             })
@@ -2269,10 +2276,12 @@ function reduceMain(
             )
 
             // Fix path highlighting after preserving first statement
-            path.forEach(pathStep => {
+            path.forEach((pathStep: any[]) => {
               pathStep.forEach((_, i) => {
                 if (i == 0) {
-                  pathStep[i] = pathStep[i].replace(/\d+/g, match => String(Number(match) + 1))
+                  pathStep[i] = pathStep[i].replace(/\d+/g, (match: any) =>
+                    String(Number(match) + 1)
+                  )
                 }
               })
             })
@@ -2483,7 +2492,7 @@ function treeifyMain(target: substituterNodes): substituterNodes {
   //   has an identifier: replace with the name
   //   else: replace with an identifer "=>"
   let verboseCount = 0
-  const treeifiers = {
+  const treeifiers: Partial<Record<substituterNodes['type'], (target: any) => any>> = {
     // Identifier: return
     ExpressionStatement: (target: es.ExpressionStatement): es.ExpressionStatement => {
       return ast.expressionStatement(treeify(target.expression) as es.Expression)
@@ -2635,7 +2644,7 @@ function jsTreeifyMain(
   //   visited before recursing to this target: replace with the name
   //   else: replace with a FunctionExpression
   let verboseCount = 0
-  const treeifiers = {
+  const treeifiers: Partial<Record<substituterNodes['type'], (target: any) => substituterNodes>> = {
     Identifier: (target: es.Identifier): es.Identifier => {
       if (readOnly && target.name.startsWith('anonymous_')) {
         return ast.identifier('[Function]')
@@ -2817,7 +2826,7 @@ function pathifyMain(
   let endIndex = path === undefined ? 0 : path.length - 1
   const redexMarker = ast.identifier('@redex') as substituterNodes
   const withBrackets = ast.identifier('(@redex)') as substituterNodes
-  const pathifiers = {
+  const pathifiers: Partial<Record<substituterNodes['type'], any>> = {
     ExpressionStatement: (target: es.ExpressionStatement): es.ExpressionStatement => {
       let exp = jsTreeifyMain(target.expression, visited, true) as es.Expression
       if (path[pathIndex] === 'expression') {
@@ -3262,9 +3271,9 @@ function substPredefinedFns(program: es.Program, context: Context): [es.Program,
 
 function substPredefinedConstants(program: es.Program): es.Program {
   const constants = [['undefined', undefined]]
-  const mathConstants = Object.getOwnPropertyNames(Math)
+  const mathConstants = objectGetOwnPropertyNames(Math)
     .filter(name => typeof Math[name] !== 'function')
-    .map(name => ['math_' + name, Math[name]])
+    .map(name => ['math_' + (name as string), Math[name]]) as (string | undefined)[][]
   let substed = program
   for (const nameValuePair of constants.concat(mathConstants)) {
     substed = substituteMain(
diff --git a/src/utils/misc.ts b/src/utils/misc.ts
index 57d362366..fa06fe3e8 100644
--- a/src/utils/misc.ts
+++ b/src/utils/misc.ts
@@ -42,3 +42,12 @@ export function objectKeys<T extends string | number | symbol>(obj: Record<T, an
 export function objectValues<T>(obj: Record<any, T>) {
   return Object.values(obj) as T[]
 }
+
+/**
+ * Type safe `Object.getOwnPropertyNames`
+ */
+export function objectGetOwnPropertyNames<T extends string | number | symbol>(
+  obj: Record<T, any>
+): T[] {
+  return Object.getOwnPropertyNames(obj) as T[]
+}
diff --git a/src/utils/uniqueIds.ts b/src/utils/uniqueIds.ts
index 348dfa149..4239d2a3b 100644
--- a/src/utils/uniqueIds.ts
+++ b/src/utils/uniqueIds.ts
@@ -20,7 +20,7 @@ const globalIdNames = [
 export type NativeIds = Record<(typeof globalIdNames)[number], es.Identifier>
 
 export function getNativeIds(program: es.Program, usedIdentifiers: Set<string>): NativeIds {
-  const globalIds = {}
+  const globalIds: Partial<NativeIds> = {}
   for (const identifier of globalIdNames) {
     globalIds[identifier] = create.identifier(getUniqueId(usedIdentifiers, identifier))
   }
diff --git a/src/vm/svml-compiler.ts b/src/vm/svml-compiler.ts
index 0710ab4eb..af3d8a7b5 100644
--- a/src/vm/svml-compiler.ts
+++ b/src/vm/svml-compiler.ts
@@ -5,9 +5,9 @@ import { ConstAssignment, UndefinedVariable } from '../errors/errors'
 import { parse } from '../parser/parser'
 import {
   CONSTANT_PRIMITIVES,
-  generatePrimitiveFunctionCode,
   INTERNAL_FUNCTIONS,
   PRIMITIVE_FUNCTION_NAMES,
+  generatePrimitiveFunctionCode,
   vmPrelude
 } from '../stdlib/vm.prelude'
 import type { Context, ContiguousArrayElements, Node } from '../types'
@@ -485,7 +485,17 @@ function compileStatements(
 }
 
 // each compiler should return a maxStackSize
-const compilers = {
+const compilers: Partial<
+  Record<
+    Node['type'],
+    (
+      node: Node,
+      indexTable: Map<string, EnvEntry>[],
+      insertFlag: boolean,
+      isTailCallPosition?: boolean
+    ) => ReturnType<typeof compileStatements>
+  >
+> = {
   // wrapper
   Program(node: Node, indexTable: Map<string, EnvEntry>[], insertFlag: boolean) {
     node = node as es.Program
diff --git a/src/vm/util.ts b/src/vm/util.ts
index 7cf9e8d23..bbd3f2f38 100644
--- a/src/vm/util.ts
+++ b/src/vm/util.ts
@@ -29,8 +29,6 @@ const OPCODES_STR = {
   [OpCodes.DIVF]: 'DIVF  ',
   [OpCodes.MODG]: 'MODG  ',
   [OpCodes.MODF]: 'MODF  ',
-  [OpCodes.NEGG]: 'NEGG  ',
-  [OpCodes.NEGF]: 'NEGF  ',
   [OpCodes.NOTG]: 'NOTG  ',
   [OpCodes.NOTB]: 'NOTB  ',
   [OpCodes.LTG]: 'LTG   ',
@@ -44,9 +42,6 @@ const OPCODES_STR = {
   [OpCodes.EQG]: 'EQG   ',
   [OpCodes.EQF]: 'EQF   ',
   [OpCodes.EQB]: 'EQB   ',
-  [OpCodes.NEQG]: 'NEQG  ',
-  [OpCodes.NEQF]: 'NEQF  ',
-  [OpCodes.NEQB]: 'NEQB  ',
   [OpCodes.NEWC]: 'NEWC  ',
   [OpCodes.NEWA]: 'NEWA  ',
   [OpCodes.LDLG]: 'LDLG  ',
@@ -156,7 +151,7 @@ const OPCODES_STR = {
 
 // get name of opcode for debugging
 export function getName(op: number) {
-  return OPCODES_STR[op] // need to add guard in case op does not exist
+  return OPCODES_STR[op as keyof typeof OPCODES_STR] // need to add guard in case op does not exist
 }
 
 // pretty-print the program
diff --git a/tsconfig.json b/tsconfig.json
index 7ee1d8ed8..3dc7bb519 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -21,7 +21,6 @@
     "noImplicitThis": true,
     "noImplicitAny": true,
     "strictNullChecks": true,
-    "suppressImplicitAnyIndexErrors": true,
     "resolveJsonModule": true,
     "noUnusedLocals": true,
     "incremental": true
diff --git a/yarn.lock b/yarn.lock
index 4971dfb12..9ba4a2515 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5812,10 +5812,10 @@ typed-array-length@^1.0.5:
     is-typed-array "^1.1.13"
     possible-typed-array-names "^1.0.0"
 
-typescript@^4.0.3:
-  version "4.9.5"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.9.5.tgz#095979f9bcc0d09da324d58d03ce8f8374cbe65a"
-  integrity sha512-1FXk9E2Hm+QzZQ7z+McJiHL4NW1F2EzMu9Nq9i3zAaGqibafqYwCVU6WyWAuyQRRzOlxou8xZSyXLEN8oKj24g==
+typescript@^5.4.5:
+  version "5.4.5"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.4.5.tgz#42ccef2c571fdbd0f6718b1d1f5e6e5ef006f611"
+  integrity sha512-vcI4UpRgg81oIRUFwR0WSIHKt11nJ7SAVlYNIu+QpqeyXP+gpQJy/Z4+F0aGxSE4MqwjyXvW/TzgkLAx2AGHwQ==
 
 uc.micro@^1.0.1, uc.micro@^1.0.5:
   version "1.0.6"