diff --git a/devtools/client/responsive.html/components/resizable-viewport.js b/devtools/client/responsive.html/components/resizable-viewport.js
index 2590d5a595ba..54ab31a85ef5 100644
--- a/devtools/client/responsive.html/components/resizable-viewport.js
+++ b/devtools/client/responsive.html/components/resizable-viewport.js
@@ -107,6 +107,8 @@ module.exports = createClass({
     // Update the viewport store with the new width and height.
     this.props.onResizeViewport(width, height);
     // Change the device selector back to an unselected device
+    // TODO: Bug 1313140: We should avoid calling this for every resize event, since it
+    // triggers RDP calls each time.
     this.props.onChangeViewportDevice({ name: "" });
 
     this.setState({
diff --git a/devtools/client/responsive.html/manager.js b/devtools/client/responsive.html/manager.js
index 4e3da02a6144..9c077bb63d01 100644
--- a/devtools/client/responsive.html/manager.js
+++ b/devtools/client/responsive.html/manager.js
@@ -471,12 +471,14 @@ ResponsiveUI.prototype = {
     this.emit("network-throttling-changed");
   }),
 
-  onChangeViewportDevice(event) {
+  onChangeViewportDevice: Task.async(function* (event) {
     let { userAgent, pixelRatio, touch } = event.data.device;
-    this.updateUserAgent(userAgent);
-    this.updateDPPX(pixelRatio);
-    this.updateTouchSimulation(touch);
-  },
+    yield this.updateUserAgent(userAgent);
+    yield this.updateDPPX(pixelRatio);
+    yield this.updateTouchSimulation(touch);
+    // Used by tests
+    this.emit("viewport-device-changed");
+  }),
 
   onContentResize(event) {
     let { width, height } = event.data;
@@ -496,13 +498,13 @@ ResponsiveUI.prototype = {
     this.updateTouchSimulation(enabled);
   },
 
-  updateDPPX(dppx) {
+  updateDPPX: Task.async(function* (dppx) {
     if (!dppx) {
-      this.emulationFront.clearDPPXOverride();
+      yield this.emulationFront.clearDPPXOverride();
       return;
     }
-    this.emulationFront.setDPPXOverride(dppx);
-  },
+    yield this.emulationFront.setDPPXOverride(dppx);
+  }),
 
   updateNetworkThrottling: Task.async(function* (enabled, profile) {
     if (!enabled) {
@@ -518,13 +520,13 @@ ResponsiveUI.prototype = {
     });
   }),
 
-  updateUserAgent(userAgent) {
+  updateUserAgent: Task.async(function* (userAgent) {
     if (!userAgent) {
-      this.emulationFront.clearUserAgentOverride();
+      yield this.emulationFront.clearUserAgentOverride();
       return;
     }
-    this.emulationFront.setUserAgentOverride(userAgent);
-  },
+    yield this.emulationFront.setUserAgentOverride(userAgent);
+  }),
 
   updateTouchSimulation: Task.async(function* (enabled) {
     if (!enabled) {
diff --git a/devtools/client/responsive.html/test/browser/browser_device_change.js b/devtools/client/responsive.html/test/browser/browser_device_change.js
index 5fd813c89ef9..936359595fcc 100644
--- a/devtools/client/responsive.html/test/browser/browser_device_change.js
+++ b/devtools/client/responsive.html/test/browser/browser_device_change.js
@@ -50,8 +50,10 @@ addRDMTask(TEST_URL, function* ({ ui, manager }) {
   yield testTouchEventsOverride(ui, true);
 
   // Test resetting device when resizing viewport
+  let deviceChanged = once(ui, "viewport-device-changed");
   yield testViewportResize(ui, ".viewport-vertical-resize-handle",
     [-10, -10], [testDevice.width, testDevice.height - 10], [0, -10], ui);
+  yield deviceChanged;
   yield testUserAgent(ui, DEFAULT_UA);
   yield testDevicePixelRatio(ui, DEFAULT_DPPX);
   yield testTouchEventsOverride(ui, false);
diff --git a/devtools/client/responsive.html/test/browser/browser_network_throttling.js b/devtools/client/responsive.html/test/browser/browser_network_throttling.js
index 092224d7b0bd..ce8d0bbb809a 100644
--- a/devtools/client/responsive.html/test/browser/browser_network_throttling.js
+++ b/devtools/client/responsive.html/test/browser/browser_network_throttling.js
@@ -25,9 +25,7 @@ addRDMTask(TEST_URL, function* ({ ui, manager }) {
   yield testThrottlingProfile(ui, "Regular 3G");
 
   // Test switching back to no throttling
-  let changed = once(ui, "network-throttling-changed");
   yield switchNetworkThrottling(ui, "No throttling");
-  yield changed;
   testNetworkThrottlingSelectorLabel(ui, "No throttling");
   yield testNetworkThrottlingState(ui, null);
 });
@@ -46,9 +44,7 @@ var testNetworkThrottlingState = Task.async(function* (ui, expected) {
 });
 
 var testThrottlingProfile = Task.async(function* (ui, profile) {
-  let changed = once(ui, "network-throttling-changed");
   yield switchNetworkThrottling(ui, profile);
-  yield changed;
   testNetworkThrottlingSelectorLabel(ui, profile);
   let data = throttlingProfiles.find(({ id }) => id == profile);
   let { download, upload, latency } = data;
diff --git a/devtools/client/responsive.html/test/browser/head.js b/devtools/client/responsive.html/test/browser/head.js
index c4b10c6eb7cc..fb7a11176557 100644
--- a/devtools/client/responsive.html/test/browser/head.js
+++ b/devtools/client/responsive.html/test/browser/head.js
@@ -198,9 +198,11 @@ function* testViewportResize(ui, selector, moveBy,
                              expectedViewportSize, expectedHandleMove) {
   let win = ui.toolWindow;
 
+  let changed = once(ui, "viewport-device-changed");
   let resized = waitForViewportResizeTo(ui, ...expectedViewportSize);
   let startRect = dragElementBy(selector, ...moveBy, win);
   yield resized;
+  yield changed;
 
   let endRect = getElRect(selector, win);
   is(endRect.left - startRect.left, expectedHandleMove[0],
@@ -256,13 +258,17 @@ function switchSelector({ toolWindow }, selector, value) {
   });
 }
 
-function switchDevice(ui, value) {
-  return switchSelector(ui, ".viewport-device-selector", value);
-}
+let switchDevice = Task.async(function* (ui, value) {
+  let changed = once(ui, "viewport-device-changed");
+  yield switchSelector(ui, ".viewport-device-selector", value);
+  yield changed;
+});
 
-function switchNetworkThrottling(ui, value) {
-  return switchSelector(ui, "#global-network-throttling-selector", value);
-}
+let switchNetworkThrottling = Task.async(function* (ui, value) {
+  let changed = once(ui, "network-throttling-changed");
+  yield switchSelector(ui, "#global-network-throttling-selector", value);
+  yield changed;
+});
 
 function getSessionHistory(browser) {
   return ContentTask.spawn(browser, {}, function* () {