diff --git a/src/components/structures/ContextMenu.tsx b/src/components/structures/ContextMenu.tsx
index 332b6cd318..4bd528b893 100644
--- a/src/components/structures/ContextMenu.tsx
+++ b/src/components/structures/ContextMenu.tsx
@@ -322,10 +322,16 @@ export class ContextMenu extends React.PureComponent<IProps, IState> {
 
         const menuClasses = classNames({
             'mx_ContextualMenu': true,
-            'mx_ContextualMenu_left': !hasChevron && position.left,
-            'mx_ContextualMenu_right': !hasChevron && position.right,
-            'mx_ContextualMenu_top': !hasChevron && position.top,
-            'mx_ContextualMenu_bottom': !hasChevron && position.bottom,
+            /**
+             * In some cases we may get the number of 0, which still means that we're supposed to properly
+             * add the specific position class, but as it was falsy things didn't work as intended.
+             * In addition, defensively check for counter cases where we may get more than one value,
+             * even if we shouldn't.
+             */
+            'mx_ContextualMenu_left': !hasChevron && position.left !== undefined && !position.right,
+            'mx_ContextualMenu_right': !hasChevron && position.right !== undefined && !position.left,
+            'mx_ContextualMenu_top': !hasChevron && position.top !== undefined && !position.bottom,
+            'mx_ContextualMenu_bottom': !hasChevron && position.bottom !== undefined && !position.top,
             'mx_ContextualMenu_withChevron_left': chevronFace === ChevronFace.Left,
             'mx_ContextualMenu_withChevron_right': chevronFace === ChevronFace.Right,
             'mx_ContextualMenu_withChevron_top': chevronFace === ChevronFace.Top,