diff --git a/README.md b/README.md
index 79103e2..c7f53b3 100644
--- a/README.md
+++ b/README.md
@@ -36,5 +36,4 @@ createMock(schema); // { name: string, age: number }
 ## TODO
 
 - ZodNever
-- ZodFunction
 - ZodLazy
\ No newline at end of file
diff --git a/lib/MockGenerator.ts b/lib/MockGenerator.ts
index 2e626b7..f00e3ae 100644
--- a/lib/MockGenerator.ts
+++ b/lib/MockGenerator.ts
@@ -30,6 +30,7 @@ import SetGenerator from './generators/SetGenerator';
 import RecordGenerator from './generators/RecordGenerator';
 import PipelineGenerator from './generators/PipelineGenerator';
 import BrandedGenerator from './generators/BrandedGenerator';
+import FunctionGenerator from './generators/FunctionGenerator';
 
 export default class MockGenerator<T extends z.ZodTypeAny> {
   private generator: BaseGenerator<TypeOf<T>>;
@@ -71,7 +72,9 @@ export default class MockGenerator<T extends z.ZodTypeAny> {
       ZodRecord: RecordGenerator,
       ZodPipeline: PipelineGenerator,
       ZodBranded: BrandedGenerator,
+      ZodFunction: FunctionGenerator,
     };
+
     if (this.schema._def.typeName in generatorMap) {
       this.generator = new generatorMap[this.schema._def.typeName as ZodFirstPartyTypeKind]();
       return;
diff --git a/lib/generators/FunctionGenerator.ts b/lib/generators/FunctionGenerator.ts
new file mode 100644
index 0000000..29b0bc2
--- /dev/null
+++ b/lib/generators/FunctionGenerator.ts
@@ -0,0 +1,10 @@
+import type { z } from 'zod';
+import MockGenerator from '../MockGenerator';
+import type BaseGenerator from './BaseGenerator';
+
+export default class FunctionGenerator<T extends z.ZodFunction<z.ZodTuple<any, any>, z.ZodTypeAny>> implements BaseGenerator<T> {
+  public generate(schema: T): z.infer<typeof schema> {
+    const mockGenerator = new MockGenerator(schema._def.returns);
+    return () => mockGenerator.generate();
+  }
+}
diff --git a/lib/index.ts b/lib/index.ts
index 5b87069..8c50218 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -2,6 +2,10 @@ import type { z } from 'zod';
 import MockGenerator from './MockGenerator';
 
 function createMock<Schema extends z.ZodTypeAny>(schema: Schema): z.infer<typeof schema> {
+  if (typeof schema === 'function') {
+    throw new TypeError('You must pass a schema to createMock');
+  }
+
   const mockGenerator = new MockGenerator(schema);
   return mockGenerator.generate();
 }
diff --git a/tests/function.test.ts b/tests/function.test.ts
new file mode 100644
index 0000000..6f03890
--- /dev/null
+++ b/tests/function.test.ts
@@ -0,0 +1,31 @@
+import { describe, test } from 'vitest';
+import { z } from 'zod';
+import { expect } from './utils/expect';
+
+describe('Function', () => {
+  test('base', () => {
+    const schema = z.function();
+
+    expect(schema);
+  });
+  test('with args as param', () => {
+    const schema = z.function(z.tuple([z.string(), z.number()]), z.boolean());
+
+    expect(schema);
+  });
+  test('with args as method', () => {
+    const schema = z.function().args(z.string(), z.number());
+
+    expect(schema);
+  });
+  test('with returns as param', () => {
+    const schema = z.function(z.tuple([z.string(), z.number()]), z.boolean());
+
+    expect(schema);
+  });
+  test('with returns as method', () => {
+    const schema = z.function().returns(z.boolean());
+
+    expect(schema);
+  });
+});