diff --git a/src/components/gui/gui.jsx b/src/components/gui/gui.jsx
index 410fe5edadb..c14060625b7 100644
--- a/src/components/gui/gui.jsx
+++ b/src/components/gui/gui.jsx
@@ -144,6 +144,8 @@ const GUIComponent = props => {
         onTelemetryModalOptOut,
         securityManager,
         showComingSoon,
+        showOpenFilePicker,
+        showSaveFilePicker,
         soundsTabVisible,
         stageSizeMode,
         targetIsStage,
@@ -302,6 +304,8 @@ const GUIComponent = props => {
                     logo={logo}
                     renderLogin={renderLogin}
                     showComingSoon={showComingSoon}
+                    showOpenFilePicker={showOpenFilePicker}
+                    showSaveFilePicker={showSaveFilePicker}
                     onClickAbout={onClickAbout}
                     onClickAccountNav={onClickAccountNav}
                     onClickAddonSettings={onClickAddonSettings}
@@ -519,6 +523,8 @@ GUIComponent.propTypes = {
     renderLogin: PropTypes.func,
     securityManager: PropTypes.shape({}),
     showComingSoon: PropTypes.bool,
+    showOpenFilePicker: PropTypes.func,
+    showSaveFilePicker: PropTypes.func,
     soundsTabVisible: PropTypes.bool,
     stageSizeMode: PropTypes.oneOf(Object.keys(STAGE_SIZE_MODES)),
     targetIsStage: PropTypes.bool,
diff --git a/src/components/menu-bar/menu-bar.jsx b/src/components/menu-bar/menu-bar.jsx
index 371ffd2c726..4ba677ab9ac 100644
--- a/src/components/menu-bar/menu-bar.jsx
+++ b/src/components/menu-bar/menu-bar.jsx
@@ -626,55 +626,61 @@ class MenuBar extends React.Component {
                                         >
                                             {this.props.intl.formatMessage(sharedMessages.loadFromComputerTitle)}
                                         </MenuItem>
-                                        <SB3Downloader>{(_className, downloadProject, extended) => (
-                                            <React.Fragment>
-                                                {extended.available && (
-                                                    <React.Fragment>
-                                                        {extended.name !== null && (
-                                                            // eslint-disable-next-line max-len
-                                                            <MenuItem onClick={this.getSaveToComputerHandler(extended.saveToLastFile)}>
+                                        <SB3Downloader
+                                            showSaveFilePicker={this.props.showSaveFilePicker}
+                                        >
+                                            {(_className, downloadProject, extended) => (
+                                                <React.Fragment>
+                                                    {extended.available && (
+                                                        <React.Fragment>
+                                                            {extended.name !== null && (
+                                                                // eslint-disable-next-line max-len
+                                                                <MenuItem onClick={this.getSaveToComputerHandler(extended.saveToLastFile)}>
+                                                                    <FormattedMessage
+                                                                        defaultMessage="Save to {file}"
+                                                                        // eslint-disable-next-line max-len
+                                                                        description="Menu bar item to save project to an existing file on the user's computer"
+                                                                        id="tw.saveTo"
+                                                                        values={{
+                                                                            file: extended.name
+                                                                        }}
+                                                                    />
+                                                                </MenuItem>
+                                                            )}
+                                                            {/* eslint-disable-next-line max-len */}
+                                                            <MenuItem onClick={this.getSaveToComputerHandler(extended.saveAsNew)}>
                                                                 <FormattedMessage
-                                                                    defaultMessage="Save to {file}"
+                                                                    defaultMessage="Save as..."
                                                                     // eslint-disable-next-line max-len
-                                                                    description="Menu bar item to save project to an existing file on the user's computer"
-                                                                    id="tw.saveTo"
-                                                                    values={{
-                                                                        file: extended.name
-                                                                    }}
+                                                                    description="Menu bar item to select a new file to save the project as"
+                                                                    id="tw.saveAs"
                                                                 />
                                                             </MenuItem>
-                                                        )}
-                                                        {/* eslint-disable-next-line max-len */}
-                                                        <MenuItem onClick={this.getSaveToComputerHandler(extended.saveAsNew)}>
-                                                            <FormattedMessage
-                                                                defaultMessage="Save as..."
-                                                                // eslint-disable-next-line max-len
-                                                                description="Menu bar item to select a new file to save the project as"
-                                                                id="tw.saveAs"
-                                                            />
+                                                        </React.Fragment>
+                                                    )}
+                                                    {notScratchDesktop() && (
+                                                        <MenuItem
+                                                            onClick={this.getSaveToComputerHandler(downloadProject)}
+                                                        >
+                                                            {extended.available ? (
+                                                                <FormattedMessage
+                                                                    defaultMessage="Save to separate file..."
+                                                                    // eslint-disable-next-line max-len
+                                                                    description="Download the project once, without being able to easily save to the same spot"
+                                                                    id="tw.oldDownload"
+                                                                />
+                                                            ) : (
+                                                                <FormattedMessage
+                                                                    defaultMessage="Save to your computer"
+                                                                    description="Menu bar item for downloading a project to your computer" // eslint-disable-line max-len
+                                                                    id="gui.menuBar.downloadToComputer"
+                                                                />
+                                                            )}
                                                         </MenuItem>
-                                                    </React.Fragment>
-                                                )}
-                                                {notScratchDesktop() && (
-                                                    <MenuItem onClick={this.getSaveToComputerHandler(downloadProject)}>
-                                                        {extended.available ? (
-                                                            <FormattedMessage
-                                                                defaultMessage="Save to separate file..."
-                                                                // eslint-disable-next-line max-len
-                                                                description="Download the project once, without being able to easily save to the same spot"
-                                                                id="tw.oldDownload"
-                                                            />
-                                                        ) : (
-                                                            <FormattedMessage
-                                                                defaultMessage="Save to your computer"
-                                                                description="Menu bar item for downloading a project to your computer" // eslint-disable-line max-len
-                                                                id="gui.menuBar.downloadToComputer"
-                                                            />
-                                                        )}
-                                                    </MenuItem>
-                                                )}
-                                            </React.Fragment>
-                                        )}</SB3Downloader>
+                                                    )}
+                                                </React.Fragment>
+                                            )}
+                                        </SB3Downloader>
                                     </MenuSection>
                                     {this.props.onClickPackager && (
                                         <MenuSection>
@@ -1125,6 +1131,7 @@ MenuBar.propTypes = {
     sessionExists: PropTypes.bool,
     settingsMenuOpen: PropTypes.bool,
     shouldSaveBeforeTransition: PropTypes.func,
+    showSaveFilePicker: PropTypes.func,
     showComingSoon: PropTypes.bool,
     username: PropTypes.string,
     userOwnsProject: PropTypes.bool,
diff --git a/src/containers/menu-bar-hoc.jsx b/src/containers/menu-bar-hoc.jsx
index 1b9407f173c..cc98745b679 100644
--- a/src/containers/menu-bar-hoc.jsx
+++ b/src/containers/menu-bar-hoc.jsx
@@ -31,14 +31,20 @@ const MenuBarHOC = function (WrappedComponent) {
                 /* eslint-enable no-unused-vars */
                 ...props
             } = this.props;
-            return (<SB3Downloader>{(_className, _downloadProject, extended) => (
-                <WrappedComponent
-                    confirmReadyToReplaceProject={this.confirmReadyToReplaceProject}
-                    shouldSaveBeforeTransition={this.shouldSaveBeforeTransition}
-                    handleSaveProject={extended.smartSave}
-                    {...props}
-                />
-            )}</SB3Downloader>);
+            return (
+                <SB3Downloader
+                    showSaveFilePicker={this.props.showSaveFilePicker}
+                >
+                    {(_className, _downloadProject, extended) => (
+                        <WrappedComponent
+                            confirmReadyToReplaceProject={this.confirmReadyToReplaceProject}
+                            shouldSaveBeforeTransition={this.shouldSaveBeforeTransition}
+                            handleSaveProject={extended.smartSave}
+                            {...props}
+                        />
+                    )}
+                </SB3Downloader>
+            );
         }
     }
 
@@ -46,7 +52,8 @@ const MenuBarHOC = function (WrappedComponent) {
         canCreateNew: PropTypes.bool,
         canSave: PropTypes.bool,
         confirmWithMessage: PropTypes.func,
-        projectChanged: PropTypes.bool
+        projectChanged: PropTypes.bool,
+        showSaveFilePicker: PropTypes.func
     };
     MenuBarContainer.defaultProps = {
         // default to using standard js confirm
diff --git a/src/containers/sb3-downloader.jsx b/src/containers/sb3-downloader.jsx
index e308f2e77f3..5cf782b8cfd 100644
--- a/src/containers/sb3-downloader.jsx
+++ b/src/containers/sb3-downloader.jsx
@@ -7,7 +7,6 @@ import downloadBlob from '../lib/download-blob';
 import {setProjectUnchanged} from '../reducers/project-changed';
 import {showStandardAlert, showAlertWithTimeout} from '../reducers/alerts';
 import {setFileHandle} from '../reducers/tw';
-import FileSystemAPI from '../lib/tw-filesystem-api';
 import {getIsShowingProject} from '../reducers/project-state';
 import log from '../lib/log';
 
@@ -97,7 +96,18 @@ class SB3Downloader extends React.Component {
             return;
         }
         try {
-            const handle = await FileSystemAPI.showSaveFilePicker(this.props.projectFilename);
+            const handle = await this.props.showSaveFilePicker({
+                suggestedName: this.props.projectFilename,
+                types: [
+                    {
+                        description: 'Scratch 3 Project',
+                        accept: {
+                            'application/x.scratch.sb3': '.sb3'
+                        }
+                    }
+                ],
+                excludeAcceptAllOption: true
+            });
             await this.saveToHandle(handle);
             this.props.onSetFileHandle(handle);
             const title = getProjectTitleFromFilename(handle.name);
@@ -241,7 +251,7 @@ class SB3Downloader extends React.Component {
         return children(
             this.props.className,
             this.downloadProject,
-            FileSystemAPI.available() ? {
+            this.props.showSaveFilePicker ? {
                 available: true,
                 name: this.props.fileHandle ? this.props.fileHandle.name : null,
                 saveAsNew: this.saveAsNew,
@@ -280,10 +290,12 @@ SB3Downloader.propTypes = {
     onShowSavingAlert: PropTypes.func,
     onShowSaveSuccessAlert: PropTypes.func,
     onShowSaveErrorAlert: PropTypes.func,
-    onProjectUnchanged: PropTypes.func
+    onProjectUnchanged: PropTypes.func,
+    showSaveFilePicker: PropTypes.func
 };
 SB3Downloader.defaultProps = {
-    className: ''
+    className: '',
+    showSaveFilePicker: typeof showSaveFilePicker === 'function' ? window.showSaveFilePicker.bind(window) : null
 };
 
 const mapStateToProps = state => ({
diff --git a/src/lib/sb-file-uploader-hoc.jsx b/src/lib/sb-file-uploader-hoc.jsx
index d740d7a7408..bbc10d29443 100644
--- a/src/lib/sb-file-uploader-hoc.jsx
+++ b/src/lib/sb-file-uploader-hoc.jsx
@@ -5,7 +5,6 @@ import {intlShape, injectIntl} from 'react-intl';
 import {connect} from 'react-redux';
 import log from '../lib/log';
 import sharedMessages from './shared-messages';
-import FileSystemAPI from './tw-filesystem-api';
 import {setFileHandle, setProjectError} from '../reducers/tw';
 
 import {
@@ -74,10 +73,20 @@ const SBFileUploaderHOC = function (WrappedComponent) {
             this.fileReader = new FileReader();
             this.fileReader.onload = this.onload;
             // tw: Use FS API when available
-            if (FileSystemAPI.available()) {
+            if (this.props.showOpenFilePicker) {
                 (async () => {
                     try {
-                        const handle = await FileSystemAPI.showOpenFilePicker();
+                        const [handle] = await this.props.showOpenFilePicker({
+                            multiple: false,
+                            types: [
+                                {
+                                    description: 'Scratch Project',
+                                    accept: {
+                                        'application/x.scratch.sb3': ['.sb', '.sb2', '.sb3']
+                                    }
+                                }
+                            ]
+                        });
                         const file = await handle.getFile();
                         this.handleChange({
                             target: {
@@ -261,6 +270,7 @@ const SBFileUploaderHOC = function (WrappedComponent) {
         onSetProjectTitle: PropTypes.func,
         projectChanged: PropTypes.bool,
         requestProjectUpload: PropTypes.func,
+        showOpenFilePicker: PropTypes.func,
         userOwnsProject: PropTypes.bool,
         vm: PropTypes.shape({
             loadProject: PropTypes.func,
@@ -271,6 +281,9 @@ const SBFileUploaderHOC = function (WrappedComponent) {
         }),
         onSetFileHandle: PropTypes.func
     };
+    SBFileUploaderComponent.defaultProps = {
+        showOpenFilePicker: typeof showOpenFilePicker === 'function' ? window.showOpenFilePicker.bind(window) : null
+    };
     const mapStateToProps = (state, ownProps) => {
         const loadingState = state.scratchGui.projectState.loadingState;
         const user = state.session && state.session.session && state.session.session.user;
diff --git a/src/lib/tw-filesystem-api.js b/src/lib/tw-filesystem-api.js
deleted file mode 100644
index 1c6cf4fcde4..00000000000
--- a/src/lib/tw-filesystem-api.js
+++ /dev/null
@@ -1,35 +0,0 @@
-const available = () => !!window.showSaveFilePicker;
-
-const showSaveFilePicker = fileName => window.showSaveFilePicker({
-    suggestedName: fileName,
-    types: [
-        {
-            description: 'Scratch 3 Project',
-            accept: {
-                'application/x.scratch.sb3': '.sb3'
-            }
-        }
-    ],
-    excludeAcceptAllOption: true
-});
-
-const showOpenFilePicker = async () => {
-    const [handle] = await window.showOpenFilePicker({
-        multiple: false,
-        types: [
-            {
-                description: 'Scratch Project',
-                accept: {
-                    'application/x.scratch.sb3': ['.sb', '.sb2', '.sb3']
-                }
-            }
-        ]
-    });
-    return handle;
-};
-
-export default {
-    available,
-    showOpenFilePicker,
-    showSaveFilePicker
-};