diff --git a/browser/devtools/debugger/test/browser_dbg_select-line.js b/browser/devtools/debugger/test/browser_dbg_select-line.js
index 0d4830f900c3..0b246593b325 100644
--- a/browser/devtools/debugger/test/browser_dbg_select-line.js
+++ b/browser/devtools/debugger/test/browser_dbg_select-line.js
@@ -73,6 +73,10 @@ function testSelectLine() {
           });
         });
 
+        // Scroll all the way down to ensure stackframe-3 is visible.
+        let stackframes = gDebugger.document.getElementById("stackframes");
+        stackframes.scrollTop = stackframes.scrollHeight;
+
         // Click the oldest stack frame.
         let frames = gDebugger.DebuggerView.Stackframes._frames;
         is(frames.querySelectorAll(".dbg-stackframe").length, 4,