diff --git a/configs/optimism.json b/configs/optimism.json
index f7ac8e6..e6f5152 100644
--- a/configs/optimism.json
+++ b/configs/optimism.json
@@ -520,5 +520,10 @@
         },
         "network": "optimism",
         "version": "git+ssh://git@github.com:perpetual-protocol/perp-curie-periphery-contract.git#a8fb8b9d6ee5836b0e652e6789c3c2469155fb2f"
+    },
+    "graft": {
+        "base": "QmVyf7ovnBMjNJioxg2Z8h22JHSgrEZd58wCwqLhV9AdG8",
+        "baseForSatsuma": "QmVyf7ovnBMjNJioxg2Z8h22JHSgrEZd58wCwqLhV9AdG8",
+        "block": 113120599
     }
 }
\ No newline at end of file
diff --git a/schema.graphql b/schema.graphql
index 9420eda..a725c1b 100644
--- a/schema.graphql
+++ b/schema.graphql
@@ -22,9 +22,9 @@ type Protocol @entity {
     "total repaid"
     totalRepaid: BigDecimal
     "threshold amount for Insurance Fund to distribute surplus"
-    insuranceFundFeeDistributionThreshold: BigDecimal!
+    insuranceFundFeeDistributionThreshold: BigDecimal
     "total amount of surplus Insurance Fund has distributed"
-    insuranceFundFeeDistributionTotalAmount: BigDecimal!
+    insuranceFundFeeDistributionTotalAmount: BigDecimal
     "last updated block number"
     blockNumber: BigInt!
     "last updated block timestamp"
diff --git a/scripts/updateConfigs.ts b/scripts/updateConfigs.ts
index 0c50cc8..2ae6dd8 100644
--- a/scripts/updateConfigs.ts
+++ b/scripts/updateConfigs.ts
@@ -48,12 +48,12 @@ async function main(): Promise<void> {
             // For Satsuma-based subgraph, log in to https://app.satsuma.xyz/
             //   -> choose target subgraph
             //   -> find "Deployment ID"
-            // graft: {
-            //     base: "QmW6xjaqSA37ZxsQ9WLp5fqReHpgXrridcWrk4DcpMqGa2",
-            //     baseForSatsuma: "QmW6xjaqSA37ZxsQ9WLp5fqReHpgXrridcWrk4DcpMqGa2",
-            //     // The block number to restore and start re-syncing from.
-            //     block: 53189383,
-            // },
+            graft: {
+                base: "QmVyf7ovnBMjNJioxg2Z8h22JHSgrEZd58wCwqLhV9AdG8",
+                baseForSatsuma: "QmVyf7ovnBMjNJioxg2Z8h22JHSgrEZd58wCwqLhV9AdG8",
+                // The block number to restore and start re-syncing from.
+                block: 113120599,
+            },
         },
     ]
 
diff --git a/src/mappings/insuranceFund.ts b/src/mappings/insuranceFund.ts
index 23e275c..bc084c6 100644
--- a/src/mappings/insuranceFund.ts
+++ b/src/mappings/insuranceFund.ts
@@ -24,7 +24,12 @@ export function handleFeeDistributed(event: FeeDistributedEvent): void {
 
     // update protocol
     const protocol = getOrCreateProtocol()
-    protocol.insuranceFundFeeDistributionTotalAmount = protocol.insuranceFundFeeDistributionTotalAmount.plus(surplus)
+    // protocol.insuranceFundFeeDistributionTotalAmount could be null due to backward compatibility
+    if (protocol.insuranceFundFeeDistributionTotalAmount !== null) {
+        protocol.insuranceFundFeeDistributionTotalAmount = protocol.insuranceFundFeeDistributionTotalAmount!.plus(surplus)
+    } else {
+        protocol.insuranceFundFeeDistributionTotalAmount = surplus
+    }
 
     // commit changes
     feeDistributed.save()