diff --git a/src/server/templates/typescript.ts b/src/server/templates/typescript.ts
index 352c4ddc..48a395cc 100644
--- a/src/server/templates/typescript.ts
+++ b/src/server/templates/typescript.ts
@@ -421,7 +421,7 @@ export const apply = async ({
               const type = typesById.get(type_id)
               let tsType = 'unknown'
               if (type) {
-                tsType = pgTypeToTsType(schema, type.name, {
+                tsType = pgTypeToTsRpcArgType(schema, type.name, {
                   types,
                   schemas,
                   tables,
@@ -440,7 +440,7 @@ export const apply = async ({
               const type = typesById.get(type_id)
               let tsType = 'unknown'
               if (type) {
-                tsType = pgTypeToTsType(schema, type.name, {
+                tsType = pgTypeToTsRpcArgType(schema, type.name, {
                   types,
                   schemas,
                   tables,
@@ -457,7 +457,7 @@ export const apply = async ({
             const type = typesById.get(type_id)
             let tsType = 'unknown'
             if (type) {
-              tsType = pgTypeToTsType(schema, type.name, {
+              tsType = pgTypeToTsRpcArgType(schema, type.name, {
                 types,
                 schemas,
                 tables,
@@ -972,3 +972,22 @@ export const pgTypeToTsType = (
     return 'unknown'
   }
 }
+
+export const pgTypeToTsRpcArgType = (
+  schema: PostgresSchema,
+  pgType: string,
+  context: {
+    types: PostgresType[]
+    schemas: PostgresSchema[]
+    tables: PostgresTable[]
+    views: PostgresView[]
+  }
+): string => {
+  if (pgType === 'int8') {
+    return 'number | bigint'
+  }
+  if (pgType.startsWith('_')) {
+    return `(${pgTypeToTsRpcArgType(schema, pgType.substring(1), context)})[]`
+  }
+  return pgTypeToTsType(schema, pgType, context)
+}
diff --git a/test/types.test.ts b/test/types.test.ts
index 8a213902..36eddc12 100644
--- a/test/types.test.ts
+++ b/test/types.test.ts
@@ -1,7 +1,7 @@
 import { expect, test, describe } from 'vitest'
 import { build } from '../src/server/app.js'
 import { TEST_CONNECTION_STRING } from './lib/utils.js'
-import { pgTypeToTsType } from '../src/server/templates/typescript'
+import { pgTypeToTsRpcArgType, pgTypeToTsType } from '../src/server/templates/typescript'
 
 describe('server/routes/types', () => {
   test('should list types', async () => {
@@ -55,4 +55,29 @@ describe('server/routes/types', () => {
 
     expect(result).toBe('string')
   })
+
+  test('int8 maps to number', () => {
+    const context = {
+      types: [],
+      schemas: [],
+      tables: [],
+      views: [],
+    }
+
+    expect(pgTypeToTsType({ name: 'public' } as any, 'int8', context)).toBe('number')
+  })
+
+  test('int8 rpc args allow bigint', () => {
+    const context = {
+      types: [],
+      schemas: [],
+      tables: [],
+      views: [],
+    }
+
+    expect(pgTypeToTsRpcArgType({ name: 'public' } as any, 'int8', context)).toBe('number | bigint')
+    expect(pgTypeToTsRpcArgType({ name: 'public' } as any, '_int8', context)).toBe(
+      '(number | bigint)[]'
+    )
+  })
 })