diff --git a/src/skins/vector/css/organisms/RoomView.css b/src/skins/vector/css/organisms/RoomView.css
index 191742f515..4a905ce703 100644
--- a/src/skins/vector/css/organisms/RoomView.css
+++ b/src/skins/vector/css/organisms/RoomView.css
@@ -107,12 +107,14 @@ limitations under the License.
 
     width: 100%;
 
+    /* specify width and margin in here rather than the wrapper otherwise gemini-scrollbars gets confused */
+    max-width: 960px;
+    margin: auto;
+
     overflow-y: auto;
 }
 
 .mx_RoomView_messageListWrapper {
-    max-width: 960px;
-    margin: auto;
 }
 
 .mx_RoomView_MessageList {
diff --git a/src/skins/vector/css/pages/MatrixChat.css b/src/skins/vector/css/pages/MatrixChat.css
index b95f6a415c..f7c63e7891 100644
--- a/src/skins/vector/css/pages/MatrixChat.css
+++ b/src/skins/vector/css/pages/MatrixChat.css
@@ -71,8 +71,14 @@ limitations under the License.
 
     background-color: #eaf5f0;
 
+/*
+    We can't use flex here as gemini-scrollbars chokes on the width calculation (on FF 42 and Chrome 48)
+    and you end up with double-scrollbars and an ever-increasing width.
+
     -webkit-flex: 0 0 210px;
     flex: 0 0 210px;
+*/
+    width: 210px;
 }
 
 .mx_MatrixChat .mx_LeftPanel.collapsed {
@@ -117,8 +123,12 @@ limitations under the License.
     -webkit-order: 3;
     order: 3;
 
+/*  Similarly, specify width explicitly otherwise gemini-scrollbars gets confused
+
     -webkit-flex: 0 0 235px;
     flex: 0 0 235px;
+*/
+    width: 235px;
 }
 
 .mx_MatrixChat .mx_RightPanel.collapsed {