--- a/devtools/client/webconsole/test/browser/browser_jsterm_screenshot_command_clipboard.js
+++ b/devtools/client/webconsole/test/browser/browser_jsterm_screenshot_command_clipboard.js
@@ -15,19 +15,16 @@ const dpr = "--dpr 1";
 
 add_task(async function() {
   const hud = await openNewTabAndConsole(TEST_URI);
   ok(hud, "web console opened");
 
   await testClipboard(hud);
   await testFullpageClipboard(hud);
   await testSelectorClipboard(hud);
-
-  // overflow
-  await createScrollbarOverflow();
   await testFullpageClipboardScrollbar(hud);
 });
 
 async function testClipboard(hud) {
   const command = `:screenshot --clipboard ${dpr}`;
   await executeScreenshotClipboardCommand(hud, command);
   const contentSize = await getContentSize();
   const imgSize = await getImageSizeFromClipboard();
@@ -80,16 +77,19 @@ async function testSelectorClipboard(hud
       imgSize.height,
       img.clientHeight,
       "Selector Clipboard: Image height matches element size"
     );
   });
 }
 
 async function testFullpageClipboardScrollbar(hud) {
+  info("Test taking a fullpage image that overflows");
+  await createScrollbarOverflow();
+
   const command = `:screenshot --fullpage --clipboard ${dpr}`;
   await executeScreenshotClipboardCommand(hud, command);
   const contentSize = await getContentSize();
   const scrollbarSize = await getScrollbarSize();
   const imgSize = await getImageSizeFromClipboard();
 
   is(
     imgSize.width,
@@ -128,16 +128,19 @@ async function createScrollbarOverflow()
   // Trigger scrollbars by forcing document to overflow
   // This only affects results on OSes with scrollbars that reduce document size
   // (non-floating scrollbars).  With default OS settings, this means Windows
   // and Linux are affected, but Mac is not.  For Mac to exhibit this behavior,
   // change System Preferences -> General -> Show scroll bars to Always.
   await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function() {
     content.document.body.classList.add("overflow");
   });
+
+  // Let's wait for next tick so scrollbars have the time to be rendered
+  await waitForTick();
 }
 
 async function getScrollbarSize() {
   const scrollbarSize = await SpecialPowers.spawn(
     gBrowser.selectedBrowser,
     [],
     function() {
       const winUtils = content.windowUtils;