diff --git a/docs-mslearn/toolkit/changelog.md b/docs-mslearn/toolkit/changelog.md
index 93e4c119d..571dedb5a 100644
--- a/docs-mslearn/toolkit/changelog.md
+++ b/docs-mslearn/toolkit/changelog.md
@@ -3,7 +3,7 @@ title: FinOps toolkit changelog
 description: Review the latest features and enhancements in the FinOps toolkit, including updates to FinOps hubs, Power BI reports, and more.
 author: MSBrett
 ms.author: brettwil
-ms.date: 10/15/2026
+ms.date: 10/16/2026
 ms.topic: reference
 ms.service: finops
 ms.subservice: finops-toolkit
@@ -43,6 +43,7 @@ The following section lists features and enhancements that are currently in deve
   - Switched dimension enrichment in the v1_0/v1_2 ingestion transforms (`PricingUnits`, `Regions`, `ResourceTypes`, `Services`) from `join` to the broadcast-optimized `lookup` operator and deduplicated the `Services` mapping per resource type to prevent cost row fan-out ([#2225](https://github.com/microsoft/finops-toolkit/pull/2225)).
   - Fixed FinOps hub dashboard "Governance, policy, and risk" and "FinOps tools and services" links that landed on a 404 page by linking directly to the Microsoft Learn pages ([#2319](https://github.com/microsoft/finops-toolkit/issues/2319)).
   - Fixed the v1_0 and v1_2 price transforms setting `x_CommitmentDiscountSpendEligibility` from reservation meters and `x_CommitmentDiscountUsageEligibility` from savings plan meters, the opposite of the FOCUS `CommitmentDiscountCategory` value the same transform assigns. The spend column now reports savings plan pricing and the usage column reports reservation pricing. Prices ingested after upgrading carry the corrected values; rows ingested earlier keep the old values until they are reingested ([#2279](https://github.com/microsoft/finops-toolkit/issues/2279)).
+  - Fixed `monthly-cost-change-percentage` returning `inf` when the prior month's cost was exactly zero. The divide-by-zero guard used `isempty()`, which is true for the null that `prev()` returns on the first row but false for `0.0`, and KQL evaluates `x / 0.0` as an infinity rather than raising. A zero prior month is reachable because `BilledCost` is zero on usage rows covered by a commitment discount ([#2323](https://github.com/microsoft/finops-toolkit/issues/2323)).
   - Fixed FinOps hubs labeling FOCUS 1.0 cost data as FOCUS 1.2 in `x_SourceVersion`. The cost transform backfilled `PricingCurrency` from `x_PricingCurrency` before detecting the FOCUS version, so every 1.0 row looked like 1.2 and skipped the 1.0-specific fixes (for example, the savings plan purchase `ChargeFrequency` correction). Version detection now uses the value delivered by the export ([#2333](https://github.com/microsoft/finops-toolkit/pull/2333)).
 
 ### [FinOps workbooks](workbooks/finops-workbooks-overview.md)
diff --git a/src/queries/catalog/monthly-cost-change-percentage.kql b/src/queries/catalog/monthly-cost-change-percentage.kql
index 0e36c8fbd..ea4664337 100644
--- a/src/queries/catalog/monthly-cost-change-percentage.kql
+++ b/src/queries/catalog/monthly-cost-change-percentage.kql
@@ -22,5 +22,5 @@ Costs()
 | extend PreviousBilledCost = prev(BilledCost)
 | extend PreviousEffectiveCost = prev(EffectiveCost)
 | project ChargePeriodStart,
-    BilledCostChangePct = iff(isempty(PreviousBilledCost), 0.0, toreal((BilledCost - PreviousBilledCost) * 100.0 / PreviousBilledCost)),
-    EffectiveCostChangePct = iff(isempty(PreviousEffectiveCost), 0.0, toreal((EffectiveCost - PreviousEffectiveCost) * 100.0 / PreviousEffectiveCost))
\ No newline at end of file
+    BilledCostChangePct = iff(isempty(PreviousBilledCost) or PreviousBilledCost == 0.0, 0.0, toreal((BilledCost - PreviousBilledCost) * 100.0 / PreviousBilledCost)),
+    EffectiveCostChangePct = iff(isempty(PreviousEffectiveCost) or PreviousEffectiveCost == 0.0, 0.0, toreal((EffectiveCost - PreviousEffectiveCost) * 100.0 / PreviousEffectiveCost))
\ No newline at end of file