@@ -1157,8 +1157,8 @@ void IndexOfString(const FunctionCallbackInfo<Value>& args) {
                                   is_forward);
   }
 
-  args.GetReturnValue().Set(result >= search_end ? -1
-                                                 : static_cast<int>(result));
+  args.GetReturnValue().Set(
+      result >= search_end ? -1 : static_cast<int64_t>(result));
 }
 
 void IndexOfBuffer(const FunctionCallbackInfo<Value>& args) {
@@ -1245,11 +1245,11 @@ void IndexOfBuffer(const FunctionCallbackInfo<Value>& args) {
                                   is_forward);
   }
 
-  args.GetReturnValue().Set(result >= search_end ? -1
-                                                 : static_cast<int>(result));
+  args.GetReturnValue().Set(
+      result >= search_end ? -1 : static_cast<int64_t>(result));
 }
 
-int32_t IndexOfNumberImpl(Local<Value> buffer_obj,
+int64_t IndexOfNumberImpl(Local<Value> buffer_obj,
                           const uint32_t needle,
                           const int64_t offset_i64,
                           const int64_t end_i64,
@@ -1276,7 +1276,7 @@ int32_t IndexOfNumberImpl(Local<Value> buffer_obj,
     ptr = nbytes::stringsearch::MemrchrFill(buffer_data, needle, backward_end);
   }
   const uint8_t* ptr_uint8 = static_cast<const uint8_t*>(ptr);
-  return ptr != nullptr ? static_cast<int32_t>(ptr_uint8 - buffer_data) : -1;
+  return ptr != nullptr ? static_cast<int64_t>(ptr_uint8 - buffer_data) : -1;
 }
 
 void SlowIndexOfNumber(const FunctionCallbackInfo<Value>& args) {
@@ -1297,7 +1297,7 @@ void SlowIndexOfNumber(const FunctionCallbackInfo<Value>& args) {
       IndexOfNumberImpl(buffer_obj, needle, offset_i64, end_i64, is_forward));
 }
 
-int32_t FastIndexOfNumber(Local<Value>,
+int64_t FastIndexOfNumber(Local<Value>,
                           Local<Value> buffer_obj,
                           uint32_t needle,
                           int64_t offset_i64,
 
@@ -0,0 +1,27 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+
+common.skipIf32Bits();
+
+const match = 2 ** 31 + 100;
+let buffer;
+try {
+  buffer = Buffer.allocUnsafe(match + 1);
+} catch (error) {
+  if (error.code === 'ERR_MEMORY_ALLOCATION_FAILED' ||
+      /Array buffer allocation failed/.test(error.message)) {
+    common.skip('insufficient space for Buffer.allocUnsafe');
+  }
+  throw error;
+}
+
+buffer[match] = 0x0a;
+
+assert.strictEqual(buffer.indexOf(0x0a, -1), match);
+assert.strictEqual(buffer.indexOf(Buffer.from([0x0a]), -1), match);
+assert.strictEqual(buffer.indexOf('\n', -1), match);
+assert.strictEqual(buffer.lastIndexOf(0x0a, -1), match);
+assert.strictEqual(buffer.lastIndexOf(Buffer.from([0x0a]), -1), match);
+assert.strictEqual(buffer.lastIndexOf('\n', -1), match);
Original file line number	Diff line number	Diff line change
`@@ -1157,8 +1157,8 @@ void IndexOfString(const FunctionCallbackInfo<Value>& args) {`
`1157`	`1157`	`is_forward);`
`1158`	`1158`	`}`
`1159`	`1159`
`1160`		`- args.GetReturnValue().Set(result >= search_end ? -1`
`1161`		`- : static_cast<int>(result));`
	`1160`	`+ args.GetReturnValue().Set(`
	`1161`	`+ result >= search_end ? -1 : static_cast<int64_t>(result));`
`1162`	`1162`	`}`
`1163`	`1163`
`1164`	`1164`	`void IndexOfBuffer(const FunctionCallbackInfo<Value>& args) {`
`@@ -1245,11 +1245,11 @@ void IndexOfBuffer(const FunctionCallbackInfo<Value>& args) {`
`1245`	`1245`	`is_forward);`
`1246`	`1246`	`}`
`1247`	`1247`
`1248`		`- args.GetReturnValue().Set(result >= search_end ? -1`
`1249`		`- : static_cast<int>(result));`
	`1248`	`+ args.GetReturnValue().Set(`
	`1249`	`+ result >= search_end ? -1 : static_cast<int64_t>(result));`
`1250`	`1250`	`}`
`1251`	`1251`
`1252`		`-int32_t IndexOfNumberImpl(Local<Value> buffer_obj,`
	`1252`	`+int64_t IndexOfNumberImpl(Local<Value> buffer_obj,`
`1253`	`1253`	`const uint32_t needle,`
`1254`	`1254`	`const int64_t offset_i64,`
`1255`	`1255`	`const int64_t end_i64,`
`@@ -1276,7 +1276,7 @@ int32_t IndexOfNumberImpl(Local<Value> buffer_obj,`
`1276`	`1276`	`ptr = nbytes::stringsearch::MemrchrFill(buffer_data, needle, backward_end);`
`1277`	`1277`	`}`
`1278`	`1278`	`const uint8_t* ptr_uint8 = static_cast<const uint8_t*>(ptr);`
`1279`		`- return ptr != nullptr ? static_cast<int32_t>(ptr_uint8 - buffer_data) : -1;`
	`1279`	`+ return ptr != nullptr ? static_cast<int64_t>(ptr_uint8 - buffer_data) : -1;`
`1280`	`1280`	`}`
`1281`	`1281`
`1282`	`1282`	`void SlowIndexOfNumber(const FunctionCallbackInfo<Value>& args) {`
`@@ -1297,7 +1297,7 @@ void SlowIndexOfNumber(const FunctionCallbackInfo<Value>& args) {`
`1297`	`1297`	`IndexOfNumberImpl(buffer_obj, needle, offset_i64, end_i64, is_forward));`
`1298`	`1298`	`}`
`1299`	`1299`
`1300`		`-int32_t FastIndexOfNumber(Local<Value>,`
	`1300`	`+int64_t FastIndexOfNumber(Local<Value>,`
`1301`	`1301`	`Local<Value> buffer_obj,`
`1302`	`1302`	`uint32_t needle,`
`1303`	`1303`	`int64_t offset_i64,`