diff --git a/apps/content/docs/openapi/input-output-structure.md b/apps/content/docs/openapi/input-output-structure.md
index 659c87aef..1e41412f7 100644
--- a/apps/content/docs/openapi/input-output-structure.md
+++ b/apps/content/docs/openapi/input-output-structure.md
@@ -96,9 +96,9 @@ export type DetailedOutput = {
 
 Make sure your handler’s return value matches this structure when using detailed mode.
 
-## Default Configuration
+## Initial Configuration
 
-Customize the default oRPC input/output structure settings using `.$route`:
+Customize the initial oRPC input/output structure settings using `.$route`:
 
 ```ts
 const base = os.$route({ inputStructure: 'detailed' })
diff --git a/apps/content/docs/openapi/routing.md b/apps/content/docs/openapi/routing.md
index 382efdc06..81bc8754f 100644
--- a/apps/content/docs/openapi/routing.md
+++ b/apps/content/docs/openapi/routing.md
@@ -66,9 +66,9 @@ const router = {
 }
 ```
 
-## Default Configuration
+## Initial Configuration
 
-Customize the default oRPC routing settings using `.$route`:
+Customize the initial oRPC routing settings using `.$route`:
 
 ```ts
 const base = os.$route({ method: 'GET' })
diff --git a/apps/content/docs/procedure.md b/apps/content/docs/procedure.md
index 9662653af..0207d9552 100644
--- a/apps/content/docs/procedure.md
+++ b/apps/content/docs/procedure.md
@@ -69,6 +69,17 @@ const example = os
 
 To learn more, see the [Middleware](/docs/middleware) documentation.
 
+## Initial Configuration
+
+Customize the initial input schema using `.$input`:
+
+```ts
+const base = os.$input(z.void())
+const base = os.$input<Schema<void, unknown>>()
+```
+
+Unlike `.input`, the `.$input` method lets you redefine the input schema after its initial configuration. This is useful when you need to enforce a `void` input when no `.input` is specified.
+
 ## Reusability
 
 Each modification to a builder creates a completely new instance, avoiding reference issues. This makes it easy to reuse and extend procedures efficiently.
diff --git a/packages/server/src/builder-variants.test-d.ts b/packages/server/src/builder-variants.test-d.ts
index 1cccf339d..86d075a14 100644
--- a/packages/server/src/builder-variants.test-d.ts
+++ b/packages/server/src/builder-variants.test-d.ts
@@ -34,7 +34,7 @@ describe('BuilderWithMiddlewares', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
             typeof generalBuilder,
-            '$config' | '$context' | '$meta' | '$route' | 'middleware'
+            '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware'
     >
 
     // expectTypeOf(builder).toMatchTypeOf(expected)
@@ -279,7 +279,7 @@ describe('ProcedureBuilder', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
         typeof generalBuilder,
-        '$config' | '$context' | '$meta' | '$route' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy'
+        '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy'
     >
 
     expectTypeOf(builder).toMatchTypeOf(expected)
@@ -458,7 +458,7 @@ describe('ProcedureBuilderWithInput', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
       typeof generalBuilder,
-      '$config' | '$context' | '$meta' | '$route' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'input'
+      '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'input'
     >
 
     expectTypeOf(builder).toMatchTypeOf(expected)
@@ -673,7 +673,7 @@ describe('ProcedureBuilderWithOutput', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
       typeof generalBuilder,
-      '$config' | '$context' | '$meta' | '$route' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'output'
+      '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'output'
     >
 
     // expectTypeOf(builder).toMatchTypeOf(expected)
@@ -839,7 +839,7 @@ describe('ProcedureBuilderWithInputOutput', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
       typeof generalBuilder,
-      '$config' | '$context' | '$meta' | '$route' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'input' | 'output'
+      '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'input' | 'output'
     >
 
     // expectTypeOf(builder).toMatchTypeOf(expected)
@@ -1039,7 +1039,7 @@ describe('RouterBuilder', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
       typeof generalBuilder,
-      '$config' | '$context' | '$meta' | '$route' | 'middleware' | 'meta' | 'route' | 'input' | 'output' | 'handler'
+      '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware' | 'meta' | 'route' | 'input' | 'output' | 'handler'
     >
 
     // expectTypeOf(builder).toMatchTypeOf(expected)
diff --git a/packages/server/src/builder.test-d.ts b/packages/server/src/builder.test-d.ts
index 75ca9a7d8..70728a104 100644
--- a/packages/server/src/builder.test-d.ts
+++ b/packages/server/src/builder.test-d.ts
@@ -11,6 +11,7 @@ import type { DecoratedMiddleware } from './middleware-decorated'
 import type { Procedure } from './procedure'
 import type { DecoratedProcedure } from './procedure-decorated'
 import type { EnhancedRouter } from './router-utils'
+import { z } from 'zod'
 import { generalSchema } from '../../contract/tests/shared'
 import { router } from '../tests/shared'
 
@@ -115,6 +116,42 @@ describe('Builder', () => {
     builder.$route({ method: 'INVALID' })
   })
 
+  describe('.$input', () => {
+    it('with actual schema', () => {
+      const schema = z.void()
+
+      expectTypeOf(builder.$input(schema)).toEqualTypeOf<
+        Builder<
+          InitialContext,
+          CurrentContext,
+          typeof schema,
+          typeof outputSchema,
+          typeof baseErrorMap,
+          BaseMeta
+        >
+      >()
+
+      // @ts-expect-error --- invalid schema
+      builder.$input({})
+    })
+
+    it('with types only', () => {
+      expectTypeOf(builder.$input<Schema<void, unknown>>()).toEqualTypeOf<
+        Builder<
+          InitialContext,
+          CurrentContext,
+          Schema<void, unknown>,
+          typeof outputSchema,
+          typeof baseErrorMap,
+          BaseMeta
+        >
+      >()
+
+      // @ts-expect-error --- invalid schema
+      builder.$input<'invalid'>()
+    })
+  })
+
   describe('.middleware', () => {
     it('works', () => {
       expectTypeOf(
diff --git a/packages/server/src/builder.test.ts b/packages/server/src/builder.test.ts
index 64e0a6db6..9173ba04a 100644
--- a/packages/server/src/builder.test.ts
+++ b/packages/server/src/builder.test.ts
@@ -1,4 +1,6 @@
+import type { Schema } from '@orpc/contract'
 import { isContractProcedure } from '@orpc/contract'
+import { z } from 'zod'
 import { baseErrorMap, baseMeta, baseRoute, generalSchema, inputSchema, outputSchema } from '../../contract/tests/shared'
 import { router } from '../tests/shared'
 import { Builder } from './builder'
@@ -94,6 +96,31 @@ describe('builder', () => {
     })
   })
 
+  describe('.$input', () => {
+    it('with actual schema', () => {
+      const schema = z.void()
+      const applied = builder.$input(schema)
+
+      expect(applied).instanceOf(Builder)
+      expect(applied).not.toBe(builder)
+      expect(applied['~orpc']).toEqual({
+        ...def,
+        inputSchema: schema,
+      })
+    })
+
+    it('with type only', () => {
+      const applied = builder.$input<Schema<void, unknown>>()
+
+      expect(applied).instanceOf(Builder)
+      expect(applied).not.toBe(builder)
+      expect(applied['~orpc']).toEqual({
+        ...def,
+        inputSchema: undefined,
+      })
+    })
+  })
+
   it('.middleware', () => {
     const mid = vi.fn()
     const applied = builder.middleware(mid)
diff --git a/packages/server/src/builder.ts b/packages/server/src/builder.ts
index cba55e09a..8851804a9 100644
--- a/packages/server/src/builder.ts
+++ b/packages/server/src/builder.ts
@@ -98,6 +98,15 @@ export class Builder<
     })
   }
 
+  $input<U extends AnySchema>(
+    initialInputSchema?: U,
+  ): Builder<TInitialContext, TCurrentContext, U, TOutputSchema, TErrorMap, TMeta> {
+    return new Builder({
+      ...this['~orpc'],
+      inputSchema: initialInputSchema,
+    })
+  }
+
   middleware<UOutContext extends Context, TInput, TOutput = any>( // = any here is important to make middleware can be used in any output by default
     middleware: Middleware<TCurrentContext, UOutContext, TInput, TOutput, ORPCErrorConstructorMap<TErrorMap>, TMeta>,
   ): DecoratedMiddleware<TCurrentContext, UOutContext, TInput, TOutput, ORPCErrorConstructorMap<any>, TMeta> { // ORPCErrorConstructorMap<any> ensures middleware can used in any procedure
diff --git a/packages/server/src/implementer-procedure.test-d.ts b/packages/server/src/implementer-procedure.test-d.ts
index bcf234ae8..05fd6a633 100644
--- a/packages/server/src/implementer-procedure.test-d.ts
+++ b/packages/server/src/implementer-procedure.test-d.ts
@@ -190,7 +190,7 @@ describe('ProcedureImplementer', () => {
   it('backward compatibility', () => {
     const expected = {} as OmitChainMethodDeep<
       typeof generalBuilder,
-      '$config' | '$context' | '$meta' | '$route' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'input' | 'output' | 'meta' | 'route' | 'errors'
+      '$config' | '$context' | '$meta' | '$route' | '$input' | 'middleware' | 'prefix' | 'tag' | 'router' | 'lazy' | 'input' | 'output' | 'meta' | 'route' | 'errors'
     >
 
     // expectTypeOf(builder).toMatchTypeOf(expected)