diff --git a/.flowconfig b/.flowconfig
index 91961148..cacdd9a7 100644
--- a/.flowconfig
+++ b/.flowconfig
@@ -1,5 +1,5 @@
 [version]
-0.133.0
+0.134.0
 
 [ignore]
 <PROJECT_ROOT>/dist
diff --git a/.yarn/sdks/flow-bin/package.json b/.yarn/sdks/flow-bin/package.json
index 87f02652..d1434259 100644
--- a/.yarn/sdks/flow-bin/package.json
+++ b/.yarn/sdks/flow-bin/package.json
@@ -1,5 +1,5 @@
 {
   "name": "flow-bin",
-  "version": "0.133.0-pnpify",
+  "version": "0.134.0-pnpify",
   "type": "commonjs"
 }
diff --git a/contrib/render-a11y-string/render-a11y-string.js b/contrib/render-a11y-string/render-a11y-string.js
index b04c4eaf..3ec0bc6f 100644
--- a/contrib/render-a11y-string/render-a11y-string.js
+++ b/contrib/render-a11y-string/render-a11y-string.js
@@ -710,7 +710,10 @@ const flatten = function(array) {
     return result;
 };
 
-const renderA11yString = function(text: string, settings?: SettingsOptions) {
+const renderA11yString = function(
+    text: string,
+    settings?: SettingsOptions,
+): string {
 
     const tree = katex.__parse(text, settings);
     const a11yStrings = buildA11yStrings(tree, [], "normal");
diff --git a/katex.js b/katex.js
index 7840ae69..9824c2db 100644
--- a/katex.js
+++ b/katex.js
@@ -25,6 +25,7 @@ import {
 
 import type {SettingsOptions} from "./src/Settings";
 import type {AnyParseNode} from "./src/parseNode";
+import type {DomSpan} from "./src/domTree";
 
 import {defineSymbol} from './src/symbols';
 import {defineMacro} from './src/macros';
@@ -36,7 +37,7 @@ declare var __VERSION__: string;
  * Parse and build an expression, and place that expression in the DOM node
  * given.
  */
-let render = function(
+let render: (string, Node, SettingsOptions) => void = function(
     expression: string,
     baseNode: Node,
     options: SettingsOptions,
@@ -109,7 +110,7 @@ const renderError = function(
 const renderToDomTree = function(
     expression: string,
     options: SettingsOptions,
-) {
+): DomSpan {
     const settings = new Settings(options);
     try {
         const tree = parseTree(expression, settings);
@@ -126,7 +127,7 @@ const renderToDomTree = function(
 const renderToHTMLTree = function(
     expression: string,
     options: SettingsOptions,
-) {
+): DomSpan {
     const settings = new Settings(options);
     try {
         const tree = parseTree(expression, settings);
diff --git a/package.json b/package.json
index 1b0320bf..c22b862c 100644
--- a/package.json
+++ b/package.json
@@ -43,7 +43,7 @@
     "eslint-plugin-flowtype": "^5.2.0",
     "eslint-plugin-react": "^7.20.3",
     "file-loader": "^6.0.0",
-    "flow-bin": "^0.133.0",
+    "flow-bin": "^0.134.0",
     "fs-extra": "^9.0.1",
     "husky": "^4.2.5",
     "istanbul-lib-coverage": "^3.0.0",
diff --git a/src/Lexer.js b/src/Lexer.js
index c7f2180d..c9271c1f 100644
--- a/src/Lexer.js
+++ b/src/Lexer.js
@@ -42,7 +42,7 @@ const controlWordWhitespaceRegexString =
 const controlWordWhitespaceRegex = new RegExp(
     `^(${controlWordRegexString})${spaceRegexString}*$`);
 const combiningDiacriticalMarkString = "[\u0300-\u036f]";
-export const combiningDiacriticalMarksEndRegex =
+export const combiningDiacriticalMarksEndRegex: RegExp =
     new RegExp(`${combiningDiacriticalMarkString}+$`);
 const tokenRegexString = `(${spaceRegexString}+)|` +  // whitespace
     "([!-\\[\\]-\u2027\u202A-\uD7FF\uF900-\uFFFF]" +  // single codepoint
diff --git a/src/Options.js b/src/Options.js
index 8f20ae02..060b9222 100644
--- a/src/Options.js
+++ b/src/Options.js
@@ -83,7 +83,7 @@ class Options {
     /**
      * The base size index.
      */
-    static BASESIZE = 6;
+    static BASESIZE: number = 6;
 
     constructor(data: OptionsData) {
         this.style = data.style;
@@ -242,7 +242,7 @@ class Options {
     /**
      * Create a new options objects with the given fontFamily.
      */
-    withTextFontFamily(fontFamily: string) {
+    withTextFontFamily(fontFamily: string): Options {
         return this.extend({
             fontFamily,
             font: "",
diff --git a/src/ParseError.js b/src/ParseError.js
index 49118be1..f0c62613 100644
--- a/src/ParseError.js
+++ b/src/ParseError.js
@@ -18,7 +18,7 @@ class ParseError {
     constructor(
         message: string,               // The error message
         token?: ?Token | AnyParseNode, // An object providing position information
-    ) {
+    ): Error {
         let error = "KaTeX parse error: " + message;
         let start;
 
diff --git a/src/Parser.js b/src/Parser.js
index a5ce3a87..c5448740 100644
--- a/src/Parser.js
+++ b/src/Parser.js
@@ -143,7 +143,7 @@ export default class Parser {
         return parse;
     }
 
-    static endOfExpression = ["}", "\\endgroup", "\\end", "\\right", "&"];
+    static endOfExpression: string[] = ["}", "\\endgroup", "\\end", "\\right", "&"];
 
     /**
      * Parses an "expression", which is a list of atoms.
diff --git a/src/Settings.js b/src/Settings.js
index 5e258c2e..c29271ae 100644
--- a/src/Settings.js
+++ b/src/Settings.js
@@ -158,7 +158,7 @@ export default class Settings {
      * This is for the second category of `errorCode`s listed in the README.
      */
     useStrictBehavior(errorCode: string, errorMsg: string,
-                      token?: Token | AnyParseNode) {
+                      token?: Token | AnyParseNode): boolean {
         let strict = this.strict;
         if (typeof strict === "function") {
             // Allow return value of strict function to be boolean or string
@@ -196,7 +196,7 @@ export default class Settings {
      * If `context` has a `url` field, a `protocol` field will automatically
      * get added by this function (changing the specified object).
      */
-    isTrusted(context: AnyTrustContext) {
+    isTrusted(context: AnyTrustContext): boolean {
         if (context.url && !context.protocol) {
             context.protocol = utils.protocolFromUrl(context.url);
         }
diff --git a/src/Style.js b/src/Style.js
index 6304c472..b77d6456 100644
--- a/src/Style.js
+++ b/src/Style.js
@@ -123,8 +123,8 @@ const text = [D, Dc, T, Tc, T, Tc, T, Tc];
 
 // We only export some of the styles.
 export default {
-    DISPLAY: styles[D],
-    TEXT: styles[T],
-    SCRIPT: styles[S],
-    SCRIPTSCRIPT: styles[SS],
+    DISPLAY: (styles[D]: Style),
+    TEXT: (styles[T]: Style),
+    SCRIPT: (styles[S]: Style),
+    SCRIPTSCRIPT: (styles[SS]: Style),
 };
diff --git a/src/Token.js b/src/Token.js
index 5ceaf168..2a84b4e7 100644
--- a/src/Token.js
+++ b/src/Token.js
@@ -41,7 +41,7 @@ export class Token {
     range(
         endToken: Token,  // last token of the range, inclusive
         text: string,     // the text of the newly constructed token
-    ) {
+    ): Token {
         return new Token(text, SourceLocation.range(this, endToken));
     }
 }
diff --git a/src/buildCommon.js b/src/buildCommon.js
index 0f8c309c..6d26beed 100644
--- a/src/buildCommon.js
+++ b/src/buildCommon.js
@@ -349,7 +349,7 @@ const makeLineSpan = function(
     className: string,
     options: Options,
     thickness?: number,
-) {
+): DomSpan {
     const line = makeSpan([className], [], options);
     line.height = Math.max(
         thickness || options.fontMetrics().defaultRuleThickness,
@@ -369,7 +369,7 @@ const makeAnchor = function(
     classes: string[],
     children: HtmlDomNode[],
     options: Options,
-) {
+): Anchor {
     const anchor = new Anchor(href, classes, children, options);
 
     sizeElementFromChildren(anchor);
diff --git a/src/functions/color.js b/src/functions/color.js
index 5c557451..ad658387 100644
--- a/src/functions/color.js
+++ b/src/functions/color.js
@@ -4,6 +4,8 @@ import buildCommon from "../buildCommon";
 import mathMLTree from "../mathMLTree";
 import {assertNodeType} from "../parseNode";
 
+import type {AnyParseNode} from '../parseNode';
+
 import * as html from "../buildHTML";
 import * as mml from "../buildMathML";
 
@@ -47,7 +49,7 @@ defineFunction({
             type: "color",
             mode: parser.mode,
             color,
-            body: ordargument(body),
+            body: (ordargument(body): AnyParseNode[]),
         };
     },
     htmlBuilder,
@@ -72,7 +74,7 @@ defineFunction({
         parser.gullet.macros.set("\\current@color", color);
 
         // Parse out the implicit body that should be colored.
-        const body = parser.parseExpression(true, breakOnTokenText);
+        const body: AnyParseNode[] = parser.parseExpression(true, breakOnTokenText);
 
         return {
             type: "color",
diff --git a/webpack.analyze.js b/webpack.analyze.js
index 76aaa7ae..02590d64 100644
--- a/webpack.analyze.js
+++ b/webpack.analyze.js
@@ -3,8 +3,8 @@ const {targets, createConfig} = require('./webpack.common');
 // $FlowIgnore
 const BundleAnalyzerPlugin = require('webpack-bundle-analyzer').BundleAnalyzerPlugin;
 
-//                                                dev   minify
-const katexConfig = createConfig(targets.shift(), false, false);
+//                                                              dev   minify
+const katexConfig /*: Object */ = createConfig(targets.shift(), false, false);
 
 katexConfig.plugins.push(new BundleAnalyzerPlugin());
 
diff --git a/webpack.common.js b/webpack.common.js
index 75e52af9..480d7421 100644
--- a/webpack.common.js
+++ b/webpack.common.js
@@ -172,6 +172,7 @@ function createConfig(target /*: Target */, dev /*: boolean */,
             plugins: [PnpWebpackPlugin],
         },
         resolveLoader: {
+            // $FlowIgnore
             plugins: [PnpWebpackPlugin.moduleLoader(module)],
         },
     };
diff --git a/webpack.config.js b/webpack.config.js
index 74fd18de..0b95027a 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -1,7 +1,7 @@
 // @flow
 const {targets, createConfig} = require('./webpack.common');
 
-module.exports = [ //                              dev   minify
+module.exports = ([ //                            dev   minify
     ...targets.map(target => createConfig(target, false, false)),
     ...targets.map(target => createConfig(target, false, true)),
-];
+] /*: Array<Object> */);
diff --git a/webpack.dev.js b/webpack.dev.js
index 11e927b4..74d2f2f2 100644
--- a/webpack.dev.js
+++ b/webpack.dev.js
@@ -3,8 +3,8 @@ const {targets, createConfig} = require('./webpack.common');
 const path = require('path');
 const PORT = 7936;
 
-//                                                dev   minify
-const katexConfig = createConfig(targets.shift(), true, false);
+//                                                             dev   minify
+const katexConfig /*: Object*/ = createConfig(targets.shift(), true, false);
 
 // add the entry point for test page
 katexConfig.entry.main = './static/main.js';
@@ -24,7 +24,7 @@ katexConfig.devServer = {
     },
 };
 
-module.exports = [
+module.exports = ([
     katexConfig,
     ...targets.map(target => createConfig(target, true, false)),
-];
+] /*: Array<Object> */);
diff --git a/yarn.lock b/yarn.lock
index fa91b0d5..f454ef68 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5345,12 +5345,12 @@ __metadata:
   languageName: node
   linkType: hard
 
-"flow-bin@npm:^0.133.0":
-  version: 0.133.0
-  resolution: "flow-bin@npm:0.133.0"
+"flow-bin@npm:^0.134.0":
+  version: 0.134.0
+  resolution: "flow-bin@npm:0.134.0"
   bin:
     flow: cli.js
-  checksum: b767946fb8763372127d7c7fd013a8c39de2066e59e19210aba17e6e7bb772bdd19f225b90466ca02bcdb2523463d59eb10d15f671d1ea024612219ed9f44fb2
+  checksum: 8858ccda62b4e7d30c1672cb48dfcd43c9421c89c692f295224090032573b1488a07abbd7cabdd9d4e2acd8792467d67e7fbeaeb0792191af772e4eae70c4010
   languageName: node
   linkType: hard
 
@@ -7657,7 +7657,7 @@ fsevents@^1.2.7:
     eslint-plugin-flowtype: ^5.2.0
     eslint-plugin-react: ^7.20.3
     file-loader: ^6.0.0
-    flow-bin: ^0.133.0
+    flow-bin: ^0.134.0
     fs-extra: ^9.0.1
     husky: ^4.2.5
     istanbul-lib-coverage: ^3.0.0