diff --git a/common/src/util/__tests__/freebuff-streak.test.ts b/common/src/util/__tests__/freebuff-streak.test.ts
index 190271a36d..2adc6227a8 100644
--- a/common/src/util/__tests__/freebuff-streak.test.ts
+++ b/common/src/util/__tests__/freebuff-streak.test.ts
@@ -5,6 +5,7 @@ import {
   calculateFreebuffStreak,
   getFreebuffDailyStreakRewardPool,
   getFreebuffStreakGlmBonusUnits,
+  getFreebuffStreakGlmWeeklyUnits,
   getFreebuffUsageDateKey,
 } from '../freebuff-streak'
 
@@ -199,4 +200,14 @@ describe('freebuff streak rewards', () => {
       }),
     ).toBeNull()
   })
+
+  test('getFreebuffStreakGlmWeeklyUnits clamps negative streaks to zero', () => {
+    // Negative streak values would produce negative bonus units without the clamp.
+    expect(getFreebuffStreakGlmWeeklyUnits(-1)).toBe(0)
+    expect(getFreebuffStreakGlmWeeklyUnits(-100)).toBe(0)
+    // Zero and positive values work as before.
+    expect(getFreebuffStreakGlmWeeklyUnits(0)).toBe(0)
+    expect(getFreebuffStreakGlmWeeklyUnits(7)).toBe(1)
+    expect(getFreebuffStreakGlmWeeklyUnits(14)).toBe(2)
+  })
 })
diff --git a/common/src/util/freebuff-streak.ts b/common/src/util/freebuff-streak.ts
index f61f22832a..d7c01068f7 100644
--- a/common/src/util/freebuff-streak.ts
+++ b/common/src/util/freebuff-streak.ts
@@ -116,8 +116,9 @@ export function isFreebuffStreakGlmBonusActive(): boolean {
  * The GLM pool resets daily since 2026-07-29 (weekly before), so these units
  * refill at that cadence. The name keeps its historical "Weekly". */
 export function getFreebuffStreakGlmWeeklyUnits(streak: number): number {
+  const safeStreak = Math.max(0, streak)
   const tiers = Math.min(
-    Math.floor(streak / FREEBUFF_STREAK_REWARD_INTERVAL_DAYS),
+    Math.floor(safeStreak / FREEBUFF_STREAK_REWARD_INTERVAL_DAYS),
     FREEBUFF_STREAK_REWARD_BONUS_MAX_MULTIPLIER,
   )
   return tiers * FREEBUFF_STREAK_BONUS_SESSION_UNITS