diff --git a/compiler/forget/src/HIR/HIRBuilder.ts b/compiler/forget/src/HIR/HIRBuilder.ts
index 94126ff410..818ad5f185 100644
--- a/compiler/forget/src/HIR/HIRBuilder.ts
+++ b/compiler/forget/src/HIR/HIRBuilder.ts
@@ -21,6 +21,7 @@ import {
   GotoVariant,
   HIR,
   Identifier,
+  IdentifierId,
   Instruction,
   makeBlockId,
   makeInstructionId,
@@ -86,7 +87,7 @@ export default class HIRBuilder {
   parentFunction: NodePath<t.Function>;
   errors: CompilerError = new CompilerError();
 
-  get nextIdentifierId() {
+  get nextIdentifierId(): IdentifierId {
     return this.#env.nextIdentifierId;
   }
 
@@ -127,7 +128,7 @@ export default class HIRBuilder {
   /**
    * Push a statement or expression onto the current block
    */
-  push(instruction: Instruction) {
+  push(instruction: Instruction): void {
     this.#current.instructions.push(instruction);
   }
 
@@ -272,7 +273,7 @@ export default class HIRBuilder {
   /**
    * Terminate the current block w the given terminal, and start a new block
    */
-  terminate(terminal: Terminal, nextBlockKind: BlockKind) {
+  terminate(terminal: Terminal, nextBlockKind: BlockKind): void {
     const { id: blockId, kind, instructions } = this.#current;
     this.#completed.set(blockId, {
       kind,
@@ -290,7 +291,7 @@ export default class HIRBuilder {
    * Terminate the current block w the given terminal, and set the previously
    * reserved block as the new current block
    */
-  terminateWithContinuation(terminal: Terminal, continuation: WipBlock) {
+  terminateWithContinuation(terminal: Terminal, continuation: WipBlock): void {
     const { id: blockId, kind, instructions } = this.#current;
     this.#completed.set(blockId, {
       kind: kind,
@@ -315,7 +316,7 @@ export default class HIRBuilder {
   /**
    * Save a previously reserved block as completed
    */
-  complete(block: WipBlock, terminal: Terminal) {
+  complete(block: WipBlock, terminal: Terminal): void {
     const { id: blockId, kind, instructions } = block;
     this.#completed.set(blockId, {
       kind,
@@ -536,7 +537,7 @@ export function removeUnreachableFallthroughs(func: HIR): void {
 export function reversePostorderBlocks(func: HIR): void {
   const visited: Set<BlockId> = new Set();
   const postorder: Array<BlockId> = [];
-  function visit(blockId: BlockId) {
+  function visit(blockId: BlockId): void {
     if (visited.has(blockId)) {
       return;
     }
@@ -634,7 +635,7 @@ export function reversePostorderBlocks(func: HIR): void {
   func.blocks = blocks;
 }
 
-export function markInstructionIds(func: HIR) {
+export function markInstructionIds(func: HIR): void {
   let id = 0;
   const visited = new Set<Instruction>();
   for (const [_, block] of func.blocks) {
@@ -650,12 +651,12 @@ export function markInstructionIds(func: HIR) {
   }
 }
 
-export function markPredecessors(func: HIR) {
+export function markPredecessors(func: HIR): void {
   for (const [, block] of func.blocks) {
     block.preds.clear();
   }
   const visited: Set<BlockId> = new Set();
-  function visit(blockId: BlockId, prevBlock: BasicBlock | null) {
+  function visit(blockId: BlockId, prevBlock: BasicBlock | null): void {
     const block = func.blocks.get(blockId)!;
     if (prevBlock) {
       block.preds.add(prevBlock.id);
diff --git a/compiler/forget/src/HIR/PrintHIR.ts b/compiler/forget/src/HIR/PrintHIR.ts
index d3146be577..8e8da1e6c4 100644
--- a/compiler/forget/src/HIR/PrintHIR.ts
+++ b/compiler/forget/src/HIR/PrintHIR.ts
@@ -42,7 +42,7 @@ export function printFunction(fn: HIRFunction): string {
 export function printHIR(ir: HIR, options: Options | null = null): string {
   let output = [];
   let indent = " ".repeat(options?.indent ?? 0);
-  const push = (text: string, indent: string = "  ") => {
+  const push = (text: string, indent: string = "  "): void => {
     output.push(`${indent}${text}`);
   };
   for (const [blockId, block] of ir.blocks) {
diff --git a/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts b/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts
index 89b3d9ab76..33ff1c90a8 100644
--- a/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts
+++ b/compiler/forget/src/ReactiveScopes/CodegenReactiveFunction.ts
@@ -416,7 +416,7 @@ function codegenDependency(
   return object;
 }
 
-function withLoc<TNode extends t.Node, T extends (...args: any[]) => TNode>(
+function withLoc<T extends (...args: any[]) => t.Node>(
   fn: T
 ): (
   loc: SourceLocation | null | undefined,
@@ -430,8 +430,7 @@ function withLoc<TNode extends t.Node, T extends (...args: any[]) => TNode>(
     if (loc != null && loc != GeneratedSource) {
       node.loc = loc;
     }
-    // @ts-ignore
-    return node;
+    return node as ReturnType<T>;
   };
 }
 
@@ -439,9 +438,9 @@ const createBinaryExpression = withLoc(t.binaryExpression);
 const createCallExpression = withLoc(t.callExpression);
 const createExpressionStatement = withLoc(t.expressionStatement);
 const createFunctionDeclaration = withLoc(t.functionDeclaration);
-const createLabelledStatement = withLoc(t.labeledStatement);
+const _createLabelledStatement = withLoc(t.labeledStatement);
 const createVariableDeclaration = withLoc(t.variableDeclaration);
-const createWhileStatement = withLoc(t.whileStatement);
+const _createWhileStatement = withLoc(t.whileStatement);
 const createTaggedTemplateExpression = withLoc(t.taggedTemplateExpression);
 const createLogicalExpression = withLoc(t.logicalExpression);
 const createSequenceExpression = withLoc(t.sequenceExpression);
diff --git a/compiler/forget/src/ReactiveScopes/visitors.ts b/compiler/forget/src/ReactiveScopes/visitors.ts
index d6a493d05c..6a5a5d8f3f 100644
--- a/compiler/forget/src/ReactiveScopes/visitors.ts
+++ b/compiler/forget/src/ReactiveScopes/visitors.ts
@@ -30,9 +30,9 @@ export function visitReactiveFunction<TState>(
 }
 
 export class ReactiveFunctionVisitor<TState = void> {
-  visitID(id: InstructionId, state: TState): void {}
-  visitLValue(id: InstructionId, lvalue: LValue, state: TState): void {}
-  visitPlace(id: InstructionId, place: Place, state: TState): void {}
+  visitID(_id: InstructionId, _state: TState): void {}
+  visitLValue(_id: InstructionId, _lvalue: LValue, _state: TState): void {}
+  visitPlace(_id: InstructionId, _place: Place, _state: TState): void {}
 
   visitValue(id: InstructionId, value: ReactiveValue, state: TState): void {
     this.traverseValue(id, value, state);
diff --git a/compiler/forget/src/SSA/EnterSSA.ts b/compiler/forget/src/SSA/EnterSSA.ts
index f573134391..89a2ce8b67 100644
--- a/compiler/forget/src/SSA/EnterSSA.ts
+++ b/compiler/forget/src/SSA/EnterSSA.ts
@@ -157,14 +157,14 @@ class SSABuilder {
     return newId;
   }
 
-  fixIncompletePhis(block: BasicBlock) {
+  fixIncompletePhis(block: BasicBlock): void {
     const state = this.#states.get(block)!;
     for (const phi of state.incompletePhis) {
       this.addPhi(block, phi.oldId, phi.newId);
     }
   }
 
-  startBlock(block: BasicBlock) {
+  startBlock(block: BasicBlock): void {
     this.#current = block;
     this.#states.set(block, {
       defs: new Map(),
@@ -172,7 +172,7 @@ class SSABuilder {
     });
   }
 
-  print() {
+  print(): void {
     const text: string[] = [];
     for (const [block, state] of this.#states) {
       text.push(`bb${block.id}:`);
@@ -194,7 +194,7 @@ class SSABuilder {
   }
 }
 
-export default function enterSSA(func: HIRFunction) {
+export default function enterSSA(func: HIRFunction): void {
   const visitedBlocks: Set<BasicBlock> = new Set();
   const builder = new SSABuilder(func.env, func.body.blocks);
   for (const [blockId, block] of func.body.blocks) {