diff --git a/src/protocol/channels.ts b/src/protocol/channels.ts
index e40c252b33..215e9952e1 100644
--- a/src/protocol/channels.ts
+++ b/src/protocol/channels.ts
@@ -1490,7 +1490,7 @@ export type FrameSetInputFilesParams = {
   files: {
     name: string,
     mimeType: string,
-    buffer: string,
+    buffer: Binary,
   }[],
   timeout?: number,
   noWaitAfter?: boolean,
@@ -1982,7 +1982,7 @@ export type ElementHandleSetInputFilesParams = {
   files: {
     name: string,
     mimeType: string,
-    buffer: string,
+    buffer: Binary,
   }[],
   timeout?: number,
   noWaitAfter?: boolean,
diff --git a/src/protocol/protocol.yml b/src/protocol/protocol.yml
index eb344adb15..3c03397add 100644
--- a/src/protocol/protocol.yml
+++ b/src/protocol/protocol.yml
@@ -1243,7 +1243,7 @@ Frame:
             properties:
               name: string
               mimeType: string
-              buffer: string
+              buffer: binary
         timeout: number?
         noWaitAfter: boolean?
 
@@ -1660,7 +1660,7 @@ ElementHandle:
             properties:
               name: string
               mimeType: string
-              buffer: string
+              buffer: binary
         timeout: number?
         noWaitAfter: boolean?
 
diff --git a/src/protocol/validator.ts b/src/protocol/validator.ts
index f07d9d45fa..8f07d900ea 100644
--- a/src/protocol/validator.ts
+++ b/src/protocol/validator.ts
@@ -592,7 +592,7 @@ export function createScheme(tChannel: (name: string) => Validator): Scheme {
     files: tArray(tObject({
       name: tString,
       mimeType: tString,
-      buffer: tString,
+      buffer: tBinary,
     })),
     timeout: tOptional(tNumber),
     noWaitAfter: tOptional(tBoolean),
@@ -781,7 +781,7 @@ export function createScheme(tChannel: (name: string) => Validator): Scheme {
     files: tArray(tObject({
       name: tString,
       mimeType: tString,
-      buffer: tString,
+      buffer: tBinary,
     })),
     timeout: tOptional(tNumber),
     noWaitAfter: tOptional(tBoolean),