diff --git a/scripts/error-codes.mjs b/scripts/error-codes.mjs
index 182434d6..5830e9ef 100644
--- a/scripts/error-codes.mjs
+++ b/scripts/error-codes.mjs
@@ -24,7 +24,8 @@ export const errorMappings = {
     16: "InvalidTarget",
     17: "InvalidTreasury",
     19: "ContractPaused",
-    20: "SelfPayout"
+    20: "SelfPayout",
+    21: "ArithmeticOverflow"
   },
   
   // Milestones contract errors
@@ -48,7 +49,8 @@ export const errorMappings = {
     17: "IssueNotAllocatedForDeallocate",
     18: "ContractPaused",
     19: "ContributionNotFound",
-    20: "SelfPayout"
+    20: "SelfPayout",
+    21: "ArithmeticOverflow"
   },
   
   // Maintenance-pool contract errors
@@ -66,7 +68,9 @@ export const errorMappings = {
     11: "NotDepositSponsor",
     12: "DepositNotFound",
     13: "ContractPaused",
-    14: "DepositCountOverflow"
+    14: "DepositCountOverflow",
+    15: "TooManyDeposits",
+    16: "ArithmeticOverflow"
   }
 };
 
diff --git a/scripts/error-codes.test.mjs b/scripts/error-codes.test.mjs
new file mode 100644
index 00000000..135c2390
--- /dev/null
+++ b/scripts/error-codes.test.mjs
@@ -0,0 +1,60 @@
+import { test, describe } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { errorMappings } from "./error-codes.mjs";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const repoRoot = path.resolve(__dirname, "..");
+
+function parseRustErrorEnum(filePath) {
+  const content = fs.readFileSync(filePath, "utf8");
+  const mapping = {};
+  const regex = /^\s*([A-Za-z0-9_]+)\s*=\s*(\d+)\s*,/gm;
+  let match;
+  while ((match = regex.exec(content)) !== null) {
+    const [, name, code] = match;
+    mapping[parseInt(code, 10)] = name;
+  }
+  return mapping;
+}
+
+describe("scripts/error-codes.mjs error mapping synchronization", () => {
+  test("escrow errorMappings matches contracts/escrow/src/error.rs", () => {
+    const rustPath = path.join(repoRoot, "contracts", "escrow", "src", "error.rs");
+    const expected = parseRustErrorEnum(rustPath);
+
+    const actual = {};
+    for (const [k, v] of Object.entries(errorMappings.escrow)) {
+      actual[parseInt(k, 10)] = v;
+    }
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  test("milestones errorMappings matches contracts/milestones/src/error.rs", () => {
+    const rustPath = path.join(repoRoot, "contracts", "milestones", "src", "error.rs");
+    const expected = parseRustErrorEnum(rustPath);
+
+    const actual = {};
+    for (const [k, v] of Object.entries(errorMappings.milestones)) {
+      actual[parseInt(k, 10)] = v;
+    }
+
+    assert.deepStrictEqual(actual, expected);
+  });
+
+  test("maintenancePool errorMappings matches contracts/maintenance-pool/src/error.rs", () => {
+    const rustPath = path.join(repoRoot, "contracts", "maintenance-pool", "src", "error.rs");
+    const expected = parseRustErrorEnum(rustPath);
+
+    const actual = {};
+    for (const [k, v] of Object.entries(errorMappings.maintenancePool)) {
+      actual[parseInt(k, 10)] = v;
+    }
+
+    assert.deepStrictEqual(actual, expected);
+  });
+});