diff --git a/res/css/structures/_RoomSubList.scss b/res/css/structures/_RoomSubList.scss
index 72b8ed4436..baecc62b2a 100644
--- a/res/css/structures/_RoomSubList.scss
+++ b/res/css/structures/_RoomSubList.scss
@@ -16,13 +16,12 @@ limitations under the License.
 
 .mx_RoomSubList {
     min-height: 80px;
-    flex: 1;
+    flex: 0;
     display: flex;
     flex-direction: column;
 }
 
 .mx_RoomSubList_hidden {
-    flex: 0;
     min-height: unset;
 }
 
diff --git a/src/components/structures/RoomSubList.js b/src/components/structures/RoomSubList.js
index 4976d3e211..e8cf5c4273 100644
--- a/src/components/structures/RoomSubList.js
+++ b/src/components/structures/RoomSubList.js
@@ -370,8 +370,9 @@ const RoomSubList = React.createClass({
                     {this._getHeaderJsx()}
                 </div>;
             } else {
+                const heightEstimation = (len * 40) + 31;
                 const GeminiScrollbarWrapper = sdk.getComponent("elements.GeminiScrollbarWrapper");
-                return <div className={"mx_RoomSubList"} style={{flexGrow: len}}>
+                return <div className={"mx_RoomSubList"} style={{flexBasis: heightEstimation}}>
                     {this._getHeaderJsx()}
                     <GeminiScrollbarWrapper>
                         { content }
diff --git a/src/resizer/sizer.js b/src/resizer/sizer.js
index fb4e860d4e..4ae35e020a 100644
--- a/src/resizer/sizer.js
+++ b/src/resizer/sizer.js
@@ -99,7 +99,6 @@ class Sizer {
 
 class FlexSizer extends Sizer {
     setItemSize(item, size) {
-        item.style.flexGrow = '0';
         item.style.flexBasis = `${Math.round(size)}px`;
     }
 }