diff --git a/src/generator/schema.ts b/src/generator/schema.ts
index 1295371b..9afeae6d 100644
--- a/src/generator/schema.ts
+++ b/src/generator/schema.ts
@@ -1,4 +1,5 @@
 import { TRPCError } from '@trpc/server';
+import e from 'express';
 import { OpenAPIV3 } from 'openapi-types';
 import { z } from 'zod';
 import zodToJsonSchema from 'zod-to-json-schema';
@@ -7,28 +8,28 @@ const zodSchemaToOpenApiSchemaObject = (zodSchema: z.ZodType): OpenAPIV3.SchemaO
   return zodToJsonSchema(zodSchema, { target: 'openApi3' });
 };
 
-const instanceofZod = (schema: any): schema is z.ZodType => {
-  return !!schema?._def?.typeName;
+const instanceofZod = (type: any): type is z.ZodType => {
+  return !!type?._def?.typeName;
 };
 
 const instanceofZodTypeKind = <Z extends z.ZodFirstPartyTypeKind>(
-  schema: any,
+  type: any,
   zodTypeKind: Z,
-): schema is InstanceType<typeof z[Z]> => {
-  return schema?._def?.typeName === zodTypeKind;
+): type is InstanceType<typeof z[Z]> => {
+  return type?._def?.typeName === zodTypeKind;
 };
 
-const getBaseZodType = (schema: z.ZodType): z.ZodType => {
-  if (instanceofZodTypeKind(schema, z.ZodFirstPartyTypeKind.ZodOptional)) {
-    return getBaseZodType(schema.unwrap());
+const unwrapZodType = (type: z.ZodType): z.ZodType => {
+  if (instanceofZodTypeKind(type, z.ZodFirstPartyTypeKind.ZodOptional)) {
+    return unwrapZodType(type.unwrap());
   }
-  if (instanceofZodTypeKind(schema, z.ZodFirstPartyTypeKind.ZodDefault)) {
-    return getBaseZodType(schema.removeDefault());
+  if (instanceofZodTypeKind(type, z.ZodFirstPartyTypeKind.ZodDefault)) {
+    return unwrapZodType(type.removeDefault());
   }
-  if (instanceofZodTypeKind(schema, z.ZodFirstPartyTypeKind.ZodEffects)) {
-    return getBaseZodType(schema.innerType());
+  if (instanceofZodTypeKind(type, z.ZodFirstPartyTypeKind.ZodEffects)) {
+    return unwrapZodType(type.innerType());
   }
-  return schema;
+  return type;
 };
 
 export const getParameterObjects = (
@@ -75,7 +76,16 @@ export const getParameterObjects = (
     .map((key) => {
       const value = shape[key]!;
 
-      if (!instanceofZodTypeKind(getBaseZodType(value), z.ZodFirstPartyTypeKind.ZodString)) {
+      const unwrappedZodType = unwrapZodType(value);
+      if (
+        !instanceofZodTypeKind(unwrappedZodType, z.ZodFirstPartyTypeKind.ZodString) &&
+        !instanceofZodTypeKind(unwrappedZodType, z.ZodFirstPartyTypeKind.ZodEnum) &&
+        !instanceofZodTypeKind(unwrappedZodType, z.ZodFirstPartyTypeKind.ZodNativeEnum) &&
+        !(
+          instanceofZodTypeKind(unwrappedZodType, z.ZodFirstPartyTypeKind.ZodLiteral) &&
+          typeof unwrappedZodType._def.value === 'string'
+        )
+      ) {
         throw new TRPCError({
           message: `Input parser key: "${key}" must be a ZodString`,
           code: 'INTERNAL_SERVER_ERROR',
diff --git a/test/generator.test.ts b/test/generator.test.ts
index 4786b4c0..604f2baa 100644
--- a/test/generator.test.ts
+++ b/test/generator.test.ts
@@ -1,5 +1,6 @@
 import * as trpc from '@trpc/server';
 import { Subscription } from '@trpc/server';
+import e from 'express';
 import openAPISchemaValidator from 'openapi-schema-validator';
 import { z } from 'zod';
 
@@ -212,7 +213,7 @@ describe('generator', () => {
     }
   });
 
-  test('with non-object-string-value input', () => {
+  test('with object-non-string-value input', () => {
     {
       const appRouter = trpc.router<any, OpenApiMeta>().query('badInput', {
         meta: { openapi: { enabled: true, path: '/bad-input', method: 'GET' } },
@@ -270,6 +271,121 @@ describe('generator', () => {
     }
   });
 
+  test('with object-enum-value input', () => {
+    enum NativeNameEnum {
+      James = 'James',
+      jlalmes = 'jlalmes',
+    }
+
+    const appRouter = trpc
+      .router<any, OpenApiMeta>()
+      .query('enum', {
+        meta: { openapi: { enabled: true, path: '/enum', method: 'GET' } },
+        input: z.object({ name: z.enum(['James', 'jlalmes']) }),
+        output: z.object({ name: z.enum(['James', 'jlalmes']) }),
+        resolve: () => ({ name: 'jlalmes' as const }),
+      })
+      .query('nativeEnum', {
+        meta: { openapi: { enabled: true, path: '/native-enum', method: 'GET' } },
+        input: z.object({ age: z.nativeEnum(NativeNameEnum) }),
+        output: z.object({ name: z.nativeEnum(NativeNameEnum) }),
+        resolve: () => ({ name: NativeNameEnum.James }),
+      });
+
+    const openApiDocument = generateOpenApiDocument(appRouter, {
+      title: 'tRPC OpenAPI',
+      version: '1.0.0',
+      baseUrl: 'http://localhost:3000/api',
+    });
+
+    expect(openApiSchemaValidator.validate(openApiDocument).errors).toEqual([]);
+    expect(openApiDocument.paths['/enum']!.get!.parameters).toMatchInlineSnapshot(`
+      Array [
+        Object {
+          "description": undefined,
+          "in": "query",
+          "name": "name",
+          "required": true,
+          "schema": Object {
+            "enum": Array [
+              "James",
+              "jlalmes",
+            ],
+            "type": "string",
+          },
+        },
+      ]
+    `);
+    expect(openApiDocument.paths['/native-enum']!.get!.parameters).toMatchInlineSnapshot(`
+      Array [
+        Object {
+          "description": undefined,
+          "in": "query",
+          "name": "age",
+          "required": true,
+          "schema": Object {
+            "enum": Array [
+              "James",
+              "jlalmes",
+            ],
+            "type": "string",
+          },
+        },
+      ]
+    `);
+  });
+
+  test('with object-literal-value input', () => {
+    {
+      const appRouter = trpc.router<any, OpenApiMeta>().query('numberLiteral', {
+        meta: { openapi: { enabled: true, path: '/number-literal', method: 'GET' } },
+        input: z.object({ num: z.literal(123) }),
+        output: z.object({ num: z.literal(123) }),
+        resolve: () => ({ num: 123 as const }),
+      });
+
+      expect(() => {
+        generateOpenApiDocument(appRouter, {
+          title: 'tRPC OpenAPI',
+          version: '1.0.0',
+          baseUrl: 'http://localhost:3000/api',
+        });
+      }).toThrowError('[query.numberLiteral] - Input parser key: "num" must be a ZodString');
+    }
+    {
+      const appRouter = trpc.router<any, OpenApiMeta>().query('stringLiteral', {
+        meta: { openapi: { enabled: true, path: '/string-literal', method: 'GET' } },
+        input: z.object({ str: z.literal('strlitval') }),
+        output: z.object({ str: z.literal('strlitval') }),
+        resolve: () => ({ str: 'strlitval' as const }),
+      });
+
+      const openApiDocument = generateOpenApiDocument(appRouter, {
+        title: 'tRPC OpenAPI',
+        version: '1.0.0',
+        baseUrl: 'http://localhost:3000/api',
+      });
+
+      expect(openApiSchemaValidator.validate(openApiDocument).errors).toEqual([]);
+      expect(openApiDocument.paths['/string-literal']!.get!.parameters).toMatchInlineSnapshot(`
+        Array [
+          Object {
+            "description": undefined,
+            "in": "query",
+            "name": "str",
+            "required": true,
+            "schema": Object {
+              "enum": Array [
+                "strlitval",
+              ],
+              "type": "string",
+            },
+          },
+        ]
+      `);
+    }
+  });
+
   test('with bad method', () => {
     {
       const appRouter = trpc.router<any, OpenApiMeta>().query('postQuery', {