diff --git a/src/parse/interfaces.ts b/src/interfaces.ts
similarity index 100%
rename from src/parse/interfaces.ts
rename to src/interfaces.ts
diff --git a/src/parse/index.ts b/src/parse/index.ts
index b169312acc..5c9e2257fe 100644
--- a/src/parse/index.ts
+++ b/src/parse/index.ts
@@ -4,29 +4,13 @@ import { whitespace } from '../utils/patterns';
 import { trimStart, trimEnd } from '../utils/trim';
 import getCodeFrame from '../utils/getCodeFrame';
 import hash from './utils/hash';
-import { Node } from './interfaces';
-
-class ParseError extends Error {
-	frame: string
-	loc: { line: number, column: number }
-	pos: number
-	filename: string
+import { Node } from '../interfaces';
+import CompileError from '../utils/CompileError'
 
+class ParseError extends CompileError {
 	constructor ( message: string, template: string, index: number, filename: string ) {
-		super( message );
-
-		const { line, column } = locate( template, index );
-
+		super( message, template, index, filename );
 		this.name = 'ParseError';
-		this.loc = { line: line + 1, column };
-		this.pos = index;
-		this.filename = filename;
-
-		this.frame = getCodeFrame( template, line, column );
-	}
-
-	toString () {
-		return `${this.message} (${this.loc.line}:${this.loc.column})\n${this.frame}`;
 	}
 }
 
diff --git a/src/parse/state/mustache.ts b/src/parse/state/mustache.ts
index a8efeb609f..afa439a45c 100644
--- a/src/parse/state/mustache.ts
+++ b/src/parse/state/mustache.ts
@@ -2,7 +2,7 @@ import readExpression from '../read/expression';
 import { whitespace } from '../../utils/patterns';
 import { trimStart, trimEnd } from '../../utils/trim';
 import { Parser } from '../index';
-import { Node } from '../interfaces';
+import { Node } from '../../interfaces';
 
 const validIdentifier = /[a-zA-Z_$][a-zA-Z0-9_$]*/;
 
diff --git a/src/parse/state/tag.ts b/src/parse/state/tag.ts
index d8c64d3be5..97d34db372 100644
--- a/src/parse/state/tag.ts
+++ b/src/parse/state/tag.ts
@@ -6,7 +6,7 @@ import { trimStart, trimEnd } from '../../utils/trim';
 import { decodeCharacterReferences } from '../utils/html';
 import isVoidElementName from '../../utils/isVoidElementName';
 import { Parser } from '../index';
-import { Node } from '../interfaces';
+import { Node } from '../../interfaces';
 
 const validTagName = /^\!?[a-zA-Z]{1,}:?[a-zA-Z0-9\-]*/;
 const invalidUnquotedAttributeCharacters = /[\s"'=<>\/`]/;
diff --git a/src/utils/CompileError.ts b/src/utils/CompileError.ts
new file mode 100644
index 0000000000..85d713dc79
--- /dev/null
+++ b/src/utils/CompileError.ts
@@ -0,0 +1,25 @@
+import { locate } from 'locate-character';
+import getCodeFrame from '../utils/getCodeFrame';
+
+export default class CompileError extends Error {
+	frame: string
+	loc: { line: number, column: number }
+	pos: number
+	filename: string
+
+	constructor ( message: string, template: string, index: number, filename: string ) {
+		super( message );
+
+		const { line, column } = locate( template, index );
+
+		this.loc = { line: line + 1, column };
+		this.pos = index;
+		this.filename = filename;
+
+		this.frame = getCodeFrame( template, line, column );
+	}
+
+	toString () {
+		return `${this.message} (${this.loc.line}:${this.loc.column})\n${this.frame}`;
+	}
+}
\ No newline at end of file
diff --git a/src/utils/isReference.ts b/src/utils/isReference.ts
index 05d216f9ad..d486cf5c26 100644
--- a/src/utils/isReference.ts
+++ b/src/utils/isReference.ts
@@ -1,4 +1,6 @@
-export default function isReference ( node, parent ): boolean {
+import { Node } from '../interfaces';
+
+export default function isReference ( node: Node, parent: Node ): boolean {
 	if ( node.type === 'MemberExpression' ) {
 		return !node.computed && isReference( node.object, node );
 	}
diff --git a/src/validate/index.ts b/src/validate/index.ts
index d9240b12eb..64c4cdb095 100644
--- a/src/validate/index.ts
+++ b/src/validate/index.ts
@@ -1,52 +1,68 @@
 import validateJs from './js/index';
 import validateHtml from './html/index';
-import { getLocator } from 'locate-character';
+import { getLocator, Location } from 'locate-character';
 import getCodeFrame from '../utils/getCodeFrame';
+import CompileError from '../utils/CompileError'
+import { Node } from '../interfaces';
 
-export default function validate ( parsed, source, { onerror, onwarn, name, filename } ) {
-	const locator = getLocator( source );
+class ValidationError extends CompileError {
+	constructor ( message: string, template: string, index: number, filename: string ) {
+		super( message, template, index, filename );
+		this.name = 'ValidationError';
+	}
+}
 
-	const validator = {
-		error: ( message, pos ) => {
-			const { line, column } = locator( pos );
+export class Validator {
+	readonly source: string;
+	readonly filename: string;
 
-			const error = new Error( message );
-			error.frame = getCodeFrame( source, line, column );
-			error.loc = { line: line + 1, column };
-			error.pos = pos;
-			error.filename = filename;
+	onwarn: ({}) => void;
+	locator?: (pos: number) => Location;
 
-			error.toString = () => `${error.message} (${error.loc.line}:${error.loc.column})\n${error.frame}`;
+	namespace: string;
+	defaultExport: Node;
+	components: Map<string, Node>;
+	methods: Map<string, Node>;
+	helpers: Map<string, Node>;
+	transitions: Map<string, Node>;
 
-			throw error;
-		},
+	constructor ( parsed, source: string, options: { onwarn, name?: string, filename?: string } ) {
+		this.source = source;
+		this.filename = options !== undefined ? options.filename : undefined;
 
-		warn: ( message, pos ) => {
-			const { line, column } = locator( pos );
+		this.onwarn = options !== undefined ? options.onwarn : undefined;
 
-			const frame = getCodeFrame( source, line, column );
+		this.namespace = null;
+		this.defaultExport = null;
+		this.properties = {};
+		this.components = new Map();
+		this.methods = new Map();
+		this.helpers = new Map();
+		this.transitions = new Map();
+	}
 
-			onwarn({
-				message,
-				frame,
-				loc: { line: line + 1, column },
-				pos,
-				filename,
-				toString: () => `${message} (${line + 1}:${column})\n${frame}`
-			});
-		},
+	error ( message: string, pos: number ) {
+		throw new ValidationError( message, this.source, pos, this.filename );
+	}
 
-		source,
+	warn ( message: string, pos: number ) {
+		if ( !this.locator ) this.locator = getLocator( this.source );
+		const { line, column } = this.locator( pos );
 
-		namespace: null,
-		defaultExport: null,
-		properties: {},
-		components: new Map(),
-		methods: new Map(),
-		helpers: new Map(),
-		transitions: new Map()
-	};
+		const frame = getCodeFrame( this.source, line, column );
 
+		this.onwarn({
+			message,
+			frame,
+			loc: { line: line + 1, column },
+			pos,
+			filename: this.filename,
+			toString: () => `${message} (${line + 1}:${column})\n${frame}`
+		});
+	}
+}
+
+export default function validate ( parsed, source, { onerror, onwarn, name, filename } ) {
 	try {
 		if ( name && !/^[a-zA-Z_$][a-zA-Z_$0-9]*$/.test( name ) ) {
 			const error = new Error( `options.name must be a valid identifier` );
@@ -62,6 +78,12 @@ export default function validate ( parsed, source, { onerror, onwarn, name, file
 			});
 		}
 
+		const validator = new Validator( parsed, source, {
+			onwarn,
+			name,
+			filename
+		});
+
 		if ( parsed.js ) {
 			validateJs( validator, parsed.js );
 		}
diff --git a/src/validate/js/index.ts b/src/validate/js/index.ts
index 9ccba4b944..44952ef5b1 100644
--- a/src/validate/js/index.ts
+++ b/src/validate/js/index.ts
@@ -3,11 +3,13 @@ import fuzzymatch from '../utils/fuzzymatch';
 import checkForDupes from './utils/checkForDupes';
 import checkForComputedKeys from './utils/checkForComputedKeys';
 import namespaces from '../../utils/namespaces';
+import { Validator } from '../';
+import { Node } from '../../interfaces';
 
 const validPropList = Object.keys( propValidators );
 
-export default function validateJs ( validator, js ) {
-	js.content.body.forEach( node => {
+export default function validateJs ( validator: Validator, js ) {
+	js.content.body.forEach( ( node: Node ) => {
 		// check there are no named exports
 		if ( node.type === 'ExportNamedDeclaration' ) {
 			validator.error( `A component can only have a default export`, node.start );
@@ -23,7 +25,7 @@ export default function validateJs ( validator, js ) {
 
 			const props = validator.properties;
 
-			node.declaration.properties.forEach( prop => {
+			node.declaration.properties.forEach( ( prop: Node ) => {
 				props[ prop.key.name ] = prop;
 			});
 
@@ -37,7 +39,7 @@ export default function validateJs ( validator, js ) {
 			}
 
 			// ensure all exported props are valid
-			node.declaration.properties.forEach( prop => {
+			node.declaration.properties.forEach( ( prop: Node ) => {
 				const propValidator = propValidators[ prop.key.name ];
 
 				if ( propValidator ) {
diff --git a/src/validate/js/propValidators/components.ts b/src/validate/js/propValidators/components.ts
index 78e9a1c57c..36077c52ed 100644
--- a/src/validate/js/propValidators/components.ts
+++ b/src/validate/js/propValidators/components.ts
@@ -1,7 +1,9 @@
 import checkForDupes from '../utils/checkForDupes';
 import checkForComputedKeys from '../utils/checkForComputedKeys';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function components ( validator, prop ) {
+export default function components ( validator: Validator, prop: Node ) {
 	if ( prop.value.type !== 'ObjectExpression' ) {
 		validator.error( `The 'components' property must be an object literal`, prop.start );
 		return;
@@ -10,7 +12,7 @@ export default function components ( validator, prop ) {
 	checkForDupes( validator, prop.value.properties );
 	checkForComputedKeys( validator, prop.value.properties );
 
-	prop.value.properties.forEach( component => {
+	prop.value.properties.forEach( ( component: Node ) => {
 		if ( component.key.name === 'state' ) {
 			validator.error( `Component constructors cannot be called 'state' due to technical limitations`, component.start );
 		}
diff --git a/src/validate/js/propValidators/computed.ts b/src/validate/js/propValidators/computed.ts
index 50e4a5c67f..c72ef26e73 100644
--- a/src/validate/js/propValidators/computed.ts
+++ b/src/validate/js/propValidators/computed.ts
@@ -1,9 +1,11 @@
 import checkForDupes from '../utils/checkForDupes';
 import checkForComputedKeys from '../utils/checkForComputedKeys';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
 const isFunctionExpression = new Set( [ 'FunctionExpression', 'ArrowFunctionExpression' ] );
 
-export default function computed ( validator, prop ) {
+export default function computed ( validator: Validator, prop: Node ) {
 	if ( prop.value.type !== 'ObjectExpression' ) {
 		validator.error( `The 'computed' property must be an object literal`, prop.start );
 		return;
@@ -12,7 +14,7 @@ export default function computed ( validator, prop ) {
 	checkForDupes( validator, prop.value.properties );
 	checkForComputedKeys( validator, prop.value.properties );
 
-	prop.value.properties.forEach( computation => {
+	prop.value.properties.forEach( ( computation: Node ) => {
 		if ( !isFunctionExpression.has( computation.value.type ) ) {
 			validator.error( `Computed properties can be function expressions or arrow function expressions`, computation.value.start );
 			return;
@@ -25,7 +27,7 @@ export default function computed ( validator, prop ) {
 			return;
 		}
 
-		params.forEach( param => {
+		params.forEach( ( param: Node ) => {
 			const valid = param.type === 'Identifier' || param.type === 'AssignmentPattern' && param.left.type === 'Identifier';
 
 			if ( !valid ) {
diff --git a/src/validate/js/propValidators/data.ts b/src/validate/js/propValidators/data.ts
index 5ea398136b..9727385a78 100644
--- a/src/validate/js/propValidators/data.ts
+++ b/src/validate/js/propValidators/data.ts
@@ -1,6 +1,9 @@
-const disallowed = new Set( [ 'Literal', 'ObjectExpression', 'ArrayExpression' ] );
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function data ( validator, prop ) {
+const disallowed = new Set([ 'Literal', 'ObjectExpression', 'ArrayExpression' ]);
+
+export default function data ( validator: Validator, prop: Node ) {
 	while ( prop.type === 'ParenthesizedExpression' ) prop = prop.expression;
 
 	// TODO should we disallow references and expressions as well?
diff --git a/src/validate/js/propValidators/events.ts b/src/validate/js/propValidators/events.ts
index 2cf8ed10b7..b1c7ecb842 100644
--- a/src/validate/js/propValidators/events.ts
+++ b/src/validate/js/propValidators/events.ts
@@ -1,7 +1,9 @@
 import checkForDupes from '../utils/checkForDupes';
 import checkForComputedKeys from '../utils/checkForComputedKeys';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function events ( validator, prop ) {
+export default function events ( validator: Validator, prop: Node ) {
 	if ( prop.value.type !== 'ObjectExpression' ) {
 		validator.error( `The 'events' property must be an object literal`, prop.start );
 		return;
diff --git a/src/validate/js/propValidators/helpers.ts b/src/validate/js/propValidators/helpers.ts
index 09cae85189..6505eb9b5e 100644
--- a/src/validate/js/propValidators/helpers.ts
+++ b/src/validate/js/propValidators/helpers.ts
@@ -1,8 +1,10 @@
 import checkForDupes from '../utils/checkForDupes';
 import checkForComputedKeys from '../utils/checkForComputedKeys';
 import { walk } from 'estree-walker';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function helpers ( validator, prop ) {
+export default function helpers ( validator: Validator, prop: Node ) {
 	if ( prop.value.type !== 'ObjectExpression' ) {
 		validator.error( `The 'helpers' property must be an object literal`, prop.start );
 		return;
@@ -11,14 +13,14 @@ export default function helpers ( validator, prop ) {
 	checkForDupes( validator, prop.value.properties );
 	checkForComputedKeys( validator, prop.value.properties );
 
-	prop.value.properties.forEach( prop => {
+	prop.value.properties.forEach( ( prop: Node ) => {
 		if ( !/FunctionExpression/.test( prop.value.type ) ) return;
 
 		let lexicalDepth = 0;
 		let usesArguments = false;
 
 		walk( prop.value.body, {
-			enter ( node ) {
+			enter ( node: Node ) {
 				if ( /^Function/.test( node.type ) ) {
 					lexicalDepth += 1;
 				}
@@ -40,7 +42,7 @@ export default function helpers ( validator, prop ) {
 				}
 			},
 
-			leave ( node ) {
+			leave ( node: Node ) {
 				if ( /^Function/.test( node.type ) ) {
 					lexicalDepth -= 1;
 				}
diff --git a/src/validate/js/propValidators/methods.ts b/src/validate/js/propValidators/methods.ts
index bf12f921b5..144a2257ee 100644
--- a/src/validate/js/propValidators/methods.ts
+++ b/src/validate/js/propValidators/methods.ts
@@ -2,10 +2,12 @@ import checkForAccessors from '../utils/checkForAccessors';
 import checkForDupes from '../utils/checkForDupes';
 import checkForComputedKeys from '../utils/checkForComputedKeys';
 import usesThisOrArguments from '../utils/usesThisOrArguments';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
 const builtin = new Set( [ 'set', 'get', 'on', 'fire', 'observe', 'destroy' ] );
 
-export default function methods ( validator, prop ) {
+export default function methods ( validator: Validator, prop: Node ) {
 	if ( prop.value.type !== 'ObjectExpression' ) {
 		validator.error( `The 'methods' property must be an object literal`, prop.start );
 		return;
@@ -15,9 +17,9 @@ export default function methods ( validator, prop ) {
 	checkForDupes( validator, prop.value.properties );
 	checkForComputedKeys( validator, prop.value.properties );
 
-	prop.value.properties.forEach( prop => {
+	prop.value.properties.forEach( ( prop: Node ) => {
 		if ( builtin.has( prop.key.name ) ) {
-			validator.error( `Cannot overwrite built-in method '${prop.key.name}'` );
+			validator.error( `Cannot overwrite built-in method '${prop.key.name}'`, prop.start );
 		}
 
 		if ( prop.value.type === 'ArrowFunctionExpression' ) {
diff --git a/src/validate/js/propValidators/namespace.ts b/src/validate/js/propValidators/namespace.ts
index a551b3f3c9..5b43bf72ea 100644
--- a/src/validate/js/propValidators/namespace.ts
+++ b/src/validate/js/propValidators/namespace.ts
@@ -1,9 +1,11 @@
 import * as namespaces from '../../../utils/namespaces';
 import fuzzymatch from '../../utils/fuzzymatch';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
 const valid = new Set( namespaces.validNamespaces );
 
-export default function namespace ( validator, prop ) {
+export default function namespace ( validator: Validator, prop: Node ) {
 	const ns = prop.value.value;
 
 	if ( prop.value.type !== 'Literal' || typeof ns !== 'string' ) {
diff --git a/src/validate/js/propValidators/oncreate.ts b/src/validate/js/propValidators/oncreate.ts
index 6481a53064..9ebf44a782 100644
--- a/src/validate/js/propValidators/oncreate.ts
+++ b/src/validate/js/propValidators/oncreate.ts
@@ -1,6 +1,8 @@
 import usesThisOrArguments from '../utils/usesThisOrArguments';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function oncreate ( validator, prop ) {
+export default function oncreate ( validator: Validator, prop: Node ) {
 	if ( prop.value.type === 'ArrowFunctionExpression' ) {
 		if ( usesThisOrArguments( prop.value.body ) ) {
 			validator.error( `'oncreate' should be a function expression, not an arrow function expression`, prop.start );
diff --git a/src/validate/js/propValidators/ondestroy.ts b/src/validate/js/propValidators/ondestroy.ts
index c65fa78d98..62155e563f 100644
--- a/src/validate/js/propValidators/ondestroy.ts
+++ b/src/validate/js/propValidators/ondestroy.ts
@@ -1,6 +1,8 @@
 import usesThisOrArguments from '../utils/usesThisOrArguments';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function ondestroy ( validator, prop ) {
+export default function ondestroy ( validator: Validator, prop: Node ) {
 	if ( prop.value.type === 'ArrowFunctionExpression' ) {
 		if ( usesThisOrArguments( prop.value.body ) ) {
 			validator.error( `'ondestroy' should be a function expression, not an arrow function expression`, prop.start );
diff --git a/src/validate/js/propValidators/onrender.ts b/src/validate/js/propValidators/onrender.ts
index d6baa00b02..0cc58c8af4 100644
--- a/src/validate/js/propValidators/onrender.ts
+++ b/src/validate/js/propValidators/onrender.ts
@@ -1,6 +1,8 @@
 import oncreate from './oncreate';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function onrender ( validator, prop ) {
+export default function onrender ( validator: Validator, prop: Node ) {
 	validator.warn( `'onrender' has been deprecated in favour of 'oncreate', and will cause an error in Svelte 2.x`, prop.start );
 	oncreate( validator, prop );
 }
diff --git a/src/validate/js/propValidators/onteardown.ts b/src/validate/js/propValidators/onteardown.ts
index fe685d2085..6c6afef7a0 100644
--- a/src/validate/js/propValidators/onteardown.ts
+++ b/src/validate/js/propValidators/onteardown.ts
@@ -1,6 +1,8 @@
 import ondestroy from './ondestroy';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function onteardown ( validator, prop ) {
+export default function onteardown ( validator: Validator, prop: Node ) {
 	validator.warn( `'onteardown' has been deprecated in favour of 'ondestroy', and will cause an error in Svelte 2.x`, prop.start );
 	ondestroy( validator, prop );
 }
diff --git a/src/validate/js/propValidators/transitions.ts b/src/validate/js/propValidators/transitions.ts
index e4de4e4bb2..b50302d93e 100644
--- a/src/validate/js/propValidators/transitions.ts
+++ b/src/validate/js/propValidators/transitions.ts
@@ -1,7 +1,9 @@
 import checkForDupes from '../utils/checkForDupes';
 import checkForComputedKeys from '../utils/checkForComputedKeys';
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
 
-export default function transitions ( validator, prop ) {
+export default function transitions ( validator: Validator, prop: Node ) {
 	if ( prop.value.type !== 'ObjectExpression' ) {
 		validator.error( `The 'transitions' property must be an object literal`, prop.start );
 		return;
diff --git a/src/validate/js/utils/checkForAccessors.ts b/src/validate/js/utils/checkForAccessors.ts
index c6fad53dc8..45ee1eb30d 100644
--- a/src/validate/js/utils/checkForAccessors.ts
+++ b/src/validate/js/utils/checkForAccessors.ts
@@ -1,4 +1,7 @@
-export default function checkForAccessors ( validator, properties, label ) {
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
+
+export default function checkForAccessors ( validator: Validator, properties: Node[], label: string ) {
 	properties.forEach( prop => {
 		if ( prop.kind !== 'init' ) {
 			validator.error( `${label} cannot use getters and setters`, prop.start );
diff --git a/src/validate/js/utils/checkForComputedKeys.ts b/src/validate/js/utils/checkForComputedKeys.ts
index f4365fde9d..ca0291e2a9 100644
--- a/src/validate/js/utils/checkForComputedKeys.ts
+++ b/src/validate/js/utils/checkForComputedKeys.ts
@@ -1,4 +1,7 @@
-export default function checkForComputedKeys ( validator, properties ) {
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
+
+export default function checkForComputedKeys ( validator: Validator, properties: Node[] ) {
 	properties.forEach( prop => {
 		if ( prop.key.computed ) {
 			validator.error( `Cannot use computed keys`, prop.start );
diff --git a/src/validate/js/utils/checkForDupes.ts b/src/validate/js/utils/checkForDupes.ts
index b35ae79159..db16a1133f 100644
--- a/src/validate/js/utils/checkForDupes.ts
+++ b/src/validate/js/utils/checkForDupes.ts
@@ -1,4 +1,7 @@
-export default function checkForDupes ( validator, properties ) {
+import { Validator } from '../../';
+import { Node } from '../../../interfaces';
+
+export default function checkForDupes ( validator: Validator, properties: Node[] ) {
 	const seen = new Set();
 
 	properties.forEach( prop => {
diff --git a/src/validate/js/utils/usesThisOrArguments.ts b/src/validate/js/utils/usesThisOrArguments.ts
index 82a0497333..2c56a57f6c 100644
--- a/src/validate/js/utils/usesThisOrArguments.ts
+++ b/src/validate/js/utils/usesThisOrArguments.ts
@@ -1,11 +1,12 @@
 import { walk } from 'estree-walker';
 import isReference from '../../../utils/isReference';
+import { Node } from '../../../interfaces';
 
-export default function usesThisOrArguments ( node ) {
+export default function usesThisOrArguments ( node: Node ) {
 	let result = false;
 
 	walk( node, {
-		enter ( node ) {
+		enter ( node: Node, parent: Node ) {
 			if ( result || node.type === 'FunctionExpression' || node.type === 'FunctionDeclaration' ) {
 				return this.skip();
 			}
@@ -14,7 +15,7 @@ export default function usesThisOrArguments ( node ) {
 				result = true;
 			}
 
-			if ( node.type === 'Identifier' && isReference( node ) && node.name === 'arguments' ) {
+			if ( node.type === 'Identifier' && isReference( node, parent ) && node.name === 'arguments' ) {
 				result = true;
 			}
 		}
diff --git a/src/validate/utils/FuzzySet.ts b/src/validate/utils/FuzzySet.ts
index f4b5d6502c..bed3ee1c13 100644
--- a/src/validate/utils/FuzzySet.ts
+++ b/src/validate/utils/FuzzySet.ts
@@ -1,4 +1,4 @@
-// adapted from https://github.com/Glench/this.js/blob/master/lib/this.js
+// adapted from https://github.com/Glench/fuzzyset.js/blob/master/lib/fuzzyset.js
 // BSD Licensed
 
 export default function FuzzySet (arr, useLevenshtein, gramSizeLower, gramSizeUpper) {
diff --git a/src/validate/utils/fuzzymatch.ts b/src/validate/utils/fuzzymatch.ts
index 756af6b94e..1769871df9 100644
--- a/src/validate/utils/fuzzymatch.ts
+++ b/src/validate/utils/fuzzymatch.ts
@@ -1,6 +1,6 @@
 import FuzzySet from './FuzzySet';
 
-export default function fuzzymatch ( name, names ) {
+export default function fuzzymatch ( name: string, names: string[] ) {
 	const set = new FuzzySet( names );
 	const matches = set.get( name );
 
diff --git a/src/validate/utils/list.ts b/src/validate/utils/list.ts
index bada8167ec..c37b6dd541 100644
--- a/src/validate/utils/list.ts
+++ b/src/validate/utils/list.ts
@@ -1,4 +1,4 @@
-export default function list ( items, conjunction = 'or' ) {
+export default function list ( items: string[], conjunction = 'or' ) {
 	if ( items.length === 1 ) return items[0];
 	return `${items.slice( 0, -1 ).join( ', ' )} ${conjunction} ${items[ items.length - 1 ]}`;
 }
\ No newline at end of file