diff --git a/package-lock.json b/package-lock.json
index 3e786cae..c44bde1b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2176,7 +2176,7 @@
     },
     "camelcase-keys": {
       "version": "2.1.0",
-      "resolved": "http://registry.npmjs.org/camelcase-keys/-/camelcase-keys-2.1.0.tgz",
+      "resolved": "https://registry.npmjs.org/camelcase-keys/-/camelcase-keys-2.1.0.tgz",
       "integrity": "sha1-MIvur/3ygRkFHvodkyITyRuPkuc=",
       "dev": true,
       "requires": {
@@ -9888,7 +9888,7 @@
     },
     "meow": {
       "version": "3.7.0",
-      "resolved": "http://registry.npmjs.org/meow/-/meow-3.7.0.tgz",
+      "resolved": "https://registry.npmjs.org/meow/-/meow-3.7.0.tgz",
       "integrity": "sha1-cstmi0JSKCkKu/qFaJJYcwioAfs=",
       "dev": true,
       "requires": {
@@ -9906,7 +9906,7 @@
       "dependencies": {
         "minimist": {
           "version": "1.2.0",
-          "resolved": "http://registry.npmjs.org/minimist/-/minimist-1.2.0.tgz",
+          "resolved": "https://registry.npmjs.org/minimist/-/minimist-1.2.0.tgz",
           "integrity": "sha1-o1AIsg9BOD7sH7kU9M1d95omQoQ=",
           "dev": true
         }
@@ -10272,7 +10272,7 @@
       "dependencies": {
         "semver": {
           "version": "5.3.0",
-          "resolved": "http://registry.npmjs.org/semver/-/semver-5.3.0.tgz",
+          "resolved": "https://registry.npmjs.org/semver/-/semver-5.3.0.tgz",
           "integrity": "sha1-myzl094C0XxgEq0yaqa00M9U+U8=",
           "dev": true
         }
@@ -12797,7 +12797,7 @@
       "dependencies": {
         "source-map": {
           "version": "0.4.4",
-          "resolved": "http://registry.npmjs.org/source-map/-/source-map-0.4.4.tgz",
+          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.4.4.tgz",
           "integrity": "sha1-66T12pwNyZneaAMti092FzZSA2s=",
           "dev": true,
           "requires": {
@@ -13726,7 +13726,7 @@
     },
     "tar": {
       "version": "2.2.1",
-      "resolved": "http://registry.npmjs.org/tar/-/tar-2.2.1.tgz",
+      "resolved": "https://registry.npmjs.org/tar/-/tar-2.2.1.tgz",
       "integrity": "sha1-jk0qJWwOIYXGsYrWlK7JaLg8sdE=",
       "dev": true,
       "requires": {
diff --git a/src/codecs/imagequant/options.tsx b/src/codecs/imagequant/options.tsx
index 875c3e9b..3af660db 100644
--- a/src/codecs/imagequant/options.tsx
+++ b/src/codecs/imagequant/options.tsx
@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldValueAsNumber, konami } from '../../lib/util';
+import { inputFieldValueAsNumber, konami, preventDefault } from '../../lib/util';
 import { QuantizeOptions } from './processor-meta';
 import * as style from '../../components/Options/style.scss';
 import Expander from '../../components/expander';
@@ -42,7 +42,7 @@ export default class QuantizerOptions extends Component<Props, State> {
 
   render({ options }: Props, { extendedSettings }: State) {
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <Expander>
           {extendedSettings ?
             <label class={style.optionTextFirst}>
diff --git a/src/codecs/mozjpeg/options.tsx b/src/codecs/mozjpeg/options.tsx
index 6fb09f6c..0cd4722f 100644
--- a/src/codecs/mozjpeg/options.tsx
+++ b/src/codecs/mozjpeg/options.tsx
@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldChecked, inputFieldValueAsNumber } from '../../lib/util';
+import { inputFieldChecked, inputFieldValueAsNumber, preventDefault } from '../../lib/util';
 import { EncodeOptions, MozJpegColorSpace } from './encoder-meta';
 import * as style from '../../components/Options/style.scss';
 import Checkbox from '../../components/checkbox';
@@ -58,7 +58,7 @@ export default class MozJPEGEncoderOptions extends Component<Props, State> {
     // I'm rendering both lossy and lossless forms, as it becomes much easier when
     // gathering the data.
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <div class={style.optionOneCell}>
           <Range
             name="quality"
diff --git a/src/codecs/optipng/options.tsx b/src/codecs/optipng/options.tsx
index 706139bb..5212707e 100644
--- a/src/codecs/optipng/options.tsx
+++ b/src/codecs/optipng/options.tsx
@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldValueAsNumber } from '../../lib/util';
+import { inputFieldValueAsNumber, preventDefault } from '../../lib/util';
 import { EncodeOptions } from './encoder-meta';
 import Range from '../../components/range';
 import * as style from '../../components/Options/style.scss';
@@ -23,7 +23,7 @@ export default class OptiPNGEncoderOptions extends Component<Props, {}> {
 
   render({ options }: Props) {
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <div class={style.optionOneCell}>
           <Range
             name="level"
diff --git a/src/codecs/resize/options.tsx b/src/codecs/resize/options.tsx
index 373dde18..42a984dd 100644
--- a/src/codecs/resize/options.tsx
+++ b/src/codecs/resize/options.tsx
@@ -1,7 +1,7 @@
 import { h, Component } from 'preact';
 import linkState from 'linkstate';
 import { bind, linkRef } from '../../lib/initial-util';
-import { inputFieldValueAsNumber, inputFieldValue } from '../../lib/util';
+import { inputFieldValueAsNumber, inputFieldValue, preventDefault } from '../../lib/util';
 import { ResizeOptions } from './processor-meta';
 import * as style from '../../components/Options/style.scss';
 import Checkbox from '../../components/checkbox';
@@ -78,7 +78,7 @@ export default class ResizerOptions extends Component<Props, State> {
 
   render({ options, isVector }: Props, { maintainAspect }: State) {
     return (
-      <form ref={linkRef(this, 'form')} class={style.optionsSection}>
+      <form ref={linkRef(this, 'form')} class={style.optionsSection} onSubmit={preventDefault}>
         <label class={style.optionTextFirst}>
           Method:
           <Select
diff --git a/src/codecs/webp/options.tsx b/src/codecs/webp/options.tsx
index f247d277..6d363ad3 100644
--- a/src/codecs/webp/options.tsx
+++ b/src/codecs/webp/options.tsx
@@ -1,6 +1,6 @@
 import { h, Component } from 'preact';
 import { bind } from '../../lib/initial-util';
-import { inputFieldCheckedAsNumber, inputFieldValueAsNumber } from '../../lib/util';
+import { inputFieldCheckedAsNumber, inputFieldValueAsNumber, preventDefault } from '../../lib/util';
 import { EncodeOptions, WebPImageHint } from './encoder-meta';
 import * as style from '../../components/Options/style.scss';
 import Checkbox from '../../components/checkbox';
@@ -319,7 +319,7 @@ export default class WebPEncoderOptions extends Component<Props, State> {
     // I'm rendering both lossy and lossless forms, as it becomes much easier when
     // gathering the data.
     return (
-      <form class={style.optionsSection}>
+      <form class={style.optionsSection} onSubmit={preventDefault}>
         <label class={style.optionInputFirst}>
           <Checkbox
             name="lossless"
diff --git a/src/lib/util.ts b/src/lib/util.ts
index 2da5d6ca..538626c8 100644
--- a/src/lib/util.ts
+++ b/src/lib/util.ts
@@ -297,3 +297,10 @@ export async function transitionHeight(el: HTMLElement, opts: TransitionOptions)
     el.addEventListener('transitioncancel', listener);
   });
 }
+
+/**
+ * Simple event listener that prevents the default.
+ */
+export function preventDefault(event: Event) {
+  event.preventDefault();
+}