diff --git a/extensions/github-copilot/login.test.ts b/extensions/github-copilot/login.test.ts
index 7aeeb2194d39..20c434443fa8 100644
--- a/extensions/github-copilot/login.test.ts
+++ b/extensions/github-copilot/login.test.ts
@@ -370,7 +370,7 @@ describe("runGitHubCopilotDeviceFlow — polling intervals", () => {
     const pollTimes: number[] = [];
     const pollResponses = [
       { error: "authorization_pending" },
-      { error: "slow_down" },
+      { error: "slow_down", interval: 7 },
       { error: "slow_down" },
       { access_token: "test-access-token", token_type: "bearer" },
     ];
diff --git a/extensions/github-copilot/login.ts b/extensions/github-copilot/login.ts
index ee0ae90807cc..8e9a371b5fd4 100644
--- a/extensions/github-copilot/login.ts
+++ b/extensions/github-copilot/login.ts
@@ -222,9 +222,11 @@ async function pollForAccessToken(params: {
       continue;
     }
     if (err === "slow_down") {
-      intervalMs =
-        positiveSecondsToSafeMilliseconds(json.interval) ??
-        Math.min(Number.MAX_SAFE_INTEGER, intervalMs + GITHUB_DEVICE_FLOW_SLOW_DOWN_INCREMENT_MS);
+      // slow_down is cumulative; a returned interval may raise but never lower the required floor.
+      intervalMs = Math.max(
+        Math.min(Number.MAX_SAFE_INTEGER, intervalMs + GITHUB_DEVICE_FLOW_SLOW_DOWN_INCREMENT_MS),
+        positiveSecondsToSafeMilliseconds(json.interval) ?? 0,
+      );
       continue;
     }
     if (err === "expired_token") {