diff --git a/.changeset/fix-suggested-fees-pct-bigint.md b/.changeset/fix-suggested-fees-pct-bigint.md
new file mode 100644
index 0000000..8f7e6ef
--- /dev/null
+++ b/.changeset/fix-suggested-fees-pct-bigint.md
@@ -0,0 +1,5 @@
+---
+"@across-protocol/app-sdk": patch
+---
+
+Tighten percentageString validator to integer strings and protect BigInt pct conversions in parseSuggestedFees
diff --git a/packages/sdk/src/actions/getSuggestedFees.ts b/packages/sdk/src/actions/getSuggestedFees.ts
index e14814d..f5fbef8 100644
--- a/packages/sdk/src/actions/getSuggestedFees.ts
+++ b/packages/sdk/src/actions/getSuggestedFees.ts
@@ -185,6 +185,10 @@ export async function getSuggestedFees({
   return parseSuggestedFees(data);
 }
 
+function toBigIntPct(value: string): bigint {
+  return BigInt(value.includes(".") ? value.split(".")[0] || "0" : value);
+}
+
 export function parseSuggestedFees(
   raw: SuggestedFeesApiResponse,
 ): GetSuggestedFeesReturnType {
@@ -209,19 +213,19 @@ export function parseSuggestedFees(
     destinationSpokePoolAddress: raw.destinationSpokePoolAddress as Address,
     fillDeadline: Number(raw.fillDeadline),
     totalRelayFee: {
-      pct: BigInt(raw.totalRelayFee.pct),
+      pct: toBigIntPct(raw.totalRelayFee.pct),
       total: BigInt(raw.totalRelayFee.total),
     },
     relayerCapitalFee: {
-      pct: BigInt(raw.relayerCapitalFee.pct),
+      pct: toBigIntPct(raw.relayerCapitalFee.pct),
       total: BigInt(raw.relayerCapitalFee.total),
     },
     relayerGasFee: {
-      pct: BigInt(raw.relayerGasFee.pct),
+      pct: toBigIntPct(raw.relayerGasFee.pct),
       total: BigInt(raw.relayerGasFee.total),
     },
     lpFee: {
-      pct: BigInt(raw.lpFee.pct),
+      pct: toBigIntPct(raw.lpFee.pct),
       total: BigInt(raw.lpFee.total),
     },
     limits: {
diff --git a/packages/sdk/src/api/validators.ts b/packages/sdk/src/api/validators.ts
index dc185e2..8b2276c 100644
--- a/packages/sdk/src/api/validators.ts
+++ b/packages/sdk/src/api/validators.ts
@@ -8,11 +8,9 @@ export const ethereumAddress = z.string().regex(/^0x[a-fA-F0-9]{40}$/, {
 });
 
 // Solana base58 address (32-44 chars)
-export const solanaAddress = z
-  .string()
-  .regex(/^[1-9A-HJ-NP-Za-km-z]{32,44}$/, {
-    message: "Invalid Solana address format",
-  });
+export const solanaAddress = z.string().regex(/^[1-9A-HJ-NP-Za-km-z]{32,44}$/, {
+  message: "Invalid Solana address format",
+});
 
 // EVM or Solana address
 export const anyChainAddress = z.union([ethereumAddress, solanaAddress]);
@@ -21,7 +19,7 @@ export const bigNumberString = z.string().regex(/^-?\d+$/, {
   message: "Invalid BigNumber string format",
 });
 
-export const percentageString = z.string().regex(/^\d+(\.\d+)?$/, {
+export const percentageString = z.string().regex(/^\d+$/, {
   message: "Invalid percentage string format",
 });
 
@@ -33,11 +31,15 @@ export const positiveIntString = z.string().regex(/^\d+$/, {
   message: "Invalid positive integer string format",
 });
 
-export const positiveFloatString = (max: number) => z.string().regex(/^\d+(\.\d+)?$/, {
-  message: "Invalid positive float string format",
-}).refine(val => parseFloat(val) <= max, {
-  message: `Value must be <= ${max}`,
-});
+export const positiveFloatString = (max: number) =>
+  z
+    .string()
+    .regex(/^\d+(\.\d+)?$/, {
+      message: "Invalid positive float string format",
+    })
+    .refine((val) => parseFloat(val) <= max, {
+      message: `Value must be <= ${max}`,
+    });
 
 export const booleanString = z.string().regex(/^(true|false)$/, {
   message: "Invalid boolean string format",
diff --git a/packages/sdk/test/unit/api/suggested-fees.test.ts b/packages/sdk/test/unit/api/suggested-fees.test.ts
index e1a4404..d826b29 100644
--- a/packages/sdk/test/unit/api/suggested-fees.test.ts
+++ b/packages/sdk/test/unit/api/suggested-fees.test.ts
@@ -1,6 +1,8 @@
+import { percentageString } from "../../../src/api/validators.js";
 import {
   getSuggestedFees,
   GetSuggestedFeesParams,
+  parseSuggestedFees,
 } from "../../../src/actions/getSuggestedFees.js";
 import { suggestedFeesResponseJsonSchema } from "../../../src/api/suggested-fees.js";
 import { MAINNET_API_URL } from "../../../src/constants/index.js";
@@ -49,4 +51,60 @@ describe("suggested-fees", async () => {
     const compareRawWithParsed = checkFields(raw, parsed);
     expect(compareRawWithParsed).toBe(true);
   });
+  test("percentageString rejects decimal strings and accepts integer strings", () => {
+    expect(percentageString.safeParse("0.5").success).toBe(false);
+    expect(percentageString.safeParse("0.0005").success).toBe(false);
+    expect(percentageString.safeParse("76950972772560").success).toBe(true);
+    expect(percentageString.safeParse("0").success).toBe(true);
+  });
+
+  test("parseSuggestedFees safely converts decimal and integer pct fields to bigint", () => {
+    const mockRaw: any = {
+      outputAmount: "1999846098054454880",
+      estimatedFillTimeSec: 3,
+      capitalFeePct: "76875000000000",
+      capitalFeeTotal: "153750000000000",
+      relayGasFeePct: "75972772560",
+      relayGasFeeTotal: "151945545120",
+      relayFeePct: "76950972772560",
+      relayFeeTotal: "153901945545120",
+      lpFeePct: "0",
+      timestamp: "1789091423",
+      isAmountTooLow: false,
+      quoteBlock: "25950980",
+      exclusiveRelayer: "0xaD03abC6223e9DEf79B3Feb624F54303A372f0c7",
+      exclusivityDeadline: 1789091551,
+      spokePoolAddress: "0x5c7BCd6E7De5423a257D81B442095A1a6ced35C5",
+      destinationSpokePoolAddress: "0x6f26Bf09B1C792e3228e5467807a900A503c0281",
+      totalRelayFee: { pct: "0.5", total: "153901945545120" },
+      relayerCapitalFee: { pct: "76875000000000", total: "153750000000000" },
+      relayerGasFee: { pct: "75972772560", total: "151945545120" },
+      lpFee: { pct: "0", total: "0" },
+      limits: {
+        minDeposit: "203996703413272",
+        maxDeposit: "1143902177198408031000",
+        maxDepositInstant: "41759844987637500165",
+        maxDepositShortDelay: "1143902177198408031000",
+        recommendedDepositInstant: "41759844987637500165",
+      },
+      fillDeadline: "1789098623",
+      inputToken: {
+        address: "0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2",
+        symbol: "WETH",
+        decimals: 18,
+        chainId: 1,
+      },
+      outputToken: {
+        address: "0x4200000000000000000000000000000000000006",
+        symbol: "WETH",
+        decimals: 18,
+        chainId: 10,
+      },
+    };
+
+    expect(() => parseSuggestedFees(mockRaw)).not.toThrow();
+    const parsed = parseSuggestedFees(mockRaw);
+    expect(parsed.totalRelayFee.pct).toBe(0n);
+    expect(parsed.relayerCapitalFee.pct).toBe(76875000000000n);
+  });
 });