diff --git a/src/actions/recomputeReduxState.js b/src/actions/recomputeReduxState.js
index 588e5dc62..a4c059e11 100644
--- a/src/actions/recomputeReduxState.js
+++ b/src/actions/recomputeReduxState.js
@@ -64,6 +64,11 @@ const modifyStateViaURLQuery = (state, query) => {
   if (query.m && state.branchLengthsToDisplay === "divAndDate") {
     state["distanceMeasure"] = query.m;
   }
+  if (query.focus === undefined) {
+    state["treeFocus"] = false;
+  } else {
+    state["treeFocus"] = true;
+  }
   if (query.c) {
     state["colorBy"] = query.c;
   }
diff --git a/src/middleware/changeURL.js b/src/middleware/changeURL.js
index a57511c7f..15c0179e7 100644
--- a/src/middleware/changeURL.js
+++ b/src/middleware/changeURL.js
@@ -140,6 +140,16 @@ export const changeURLMiddleware = (store) => (next) => (action) => {
       query.p = action.notInURLState === true ? undefined : action.data;
       break;
     }
+    case types.TOGGLE_TREE_FOCUS: {
+      // "null" is truthy - see query.ci implementation
+      if ("focus" in action) {
+        query.focus = action.focus ? null : undefined
+      }
+      else {
+        query.focus = ("focus" in query) ? undefined : null;
+      }
+      break;
+    }
     case types.TOGGLE_SIDEBAR: {
       // we never add this to the URL on purpose -- it should be manually set as it specifies a world
       // where resizes can not open / close the sidebar. The exception is if it's toggled, we