diff --git a/src/components/views/spaces/SpaceTreeLevel.tsx b/src/components/views/spaces/SpaceTreeLevel.tsx
index b3577e436a..cbc1cab86b 100644
--- a/src/components/views/spaces/SpaceTreeLevel.tsx
+++ b/src/components/views/spaces/SpaceTreeLevel.tsx
@@ -409,6 +409,8 @@ export class SpaceItem extends React.PureComponent<IItemProps, IItemState> {
             <AccessibleButton
                 className="mx_SpaceButton_toggleCollapse"
                 onClick={this.toggleCollapse}
+                tabIndex={-1}
+                aria-label={collapsed ? _t("Expand") : _t("Collapse")}
             /> : null;
 
         return (
@@ -420,6 +422,7 @@ export class SpaceItem extends React.PureComponent<IItemProps, IItemState> {
                     onContextMenu={this.onContextMenu}
                     forceHide={!isNarrow || !!this.state.contextMenuPosition}
                     role="treeitem"
+                    aria-expanded={!collapsed}
                     inputRef={this.buttonRef}
                     onKeyDown={this.onKeyDown}
                 >
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index b88dc79da5..a2fb93dc17 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -1038,6 +1038,8 @@
     "Manage & explore rooms": "Manage & explore rooms",
     "Explore rooms": "Explore rooms",
     "Space options": "Space options",
+    "Expand": "Expand",
+    "Collapse": "Collapse",
     "Remove": "Remove",
     "This bridge was provisioned by <user />.": "This bridge was provisioned by <user />.",
     "This bridge is managed by <user />.": "This bridge is managed by <user />.",