diff --git a/go.mod b/go.mod
index a91430df5..fbdf0ac5f 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,6 @@ require (
 	github.com/andygrunwald/go-gerrit v0.0.0-20230628115649-c44fe2fbf2ca
 	github.com/bmatcuk/doublestar v1.3.4
 	github.com/dustin/go-humanize v1.0.1
-	github.com/edsrzf/mmap-go v1.1.0
 	github.com/felixge/fgprof v0.9.3
 	github.com/fsnotify/fsnotify v1.6.0
 	github.com/gfleury/go-bitbucket-v1 v0.0.0-20230626192437-8d7be5866751
diff --git a/go.sum b/go.sum
index b85a4d272..e12f6305e 100644
--- a/go.sum
+++ b/go.sum
@@ -78,8 +78,6 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
-github.com/edsrzf/mmap-go v1.1.0 h1:6EUwBLQ/Mcr1EYLE4Tn1VdW1A4ckqCQWZBw8Hr0kjpQ=
-github.com/edsrzf/mmap-go v1.1.0/go.mod h1:19H/e8pUPLicwkyNgOykDXkJ9F0MHE+Z52B8EIth78Q=
 github.com/elazarl/goproxy v0.0.0-20221015165544-a0805db90819 h1:RIB4cRk+lBqKK3Oy0r2gRX4ui7tuhiZq2SuTtTCi0/0=
 github.com/elazarl/goproxy v0.0.0-20221015165544-a0805db90819/go.mod h1:Ro8st/ElPeALwNFlcTpWmkr6IoMFfkjXAvTHpevnDsM=
 github.com/emirpasic/gods v1.18.1 h1:FXtiHYKDGKCW2KzwZKx0iC0PQmdlorYgdFG9jPXJ1Bc=
diff --git a/indexfile_other.go b/indexfile_other.go
new file mode 100644
index 000000000..f192d9beb
--- /dev/null
+++ b/indexfile_other.go
@@ -0,0 +1,62 @@
+// Copyright 2016 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !linux && !darwin
+// +build !linux,!darwin
+
+package zoekt
+
+import (
+	"fmt"
+	"os"
+)
+
+// NewIndexFile returns a new index file. The index file takes
+// ownership of the passed in file, and may close it.
+func NewIndexFile(f *os.File) (IndexFile, error) {
+	return &indexFileFromOS{f}, nil
+}
+
+type indexFileFromOS struct {
+	f *os.File
+}
+
+func (f *indexFileFromOS) Read(off, sz uint32) ([]byte, error) {
+	r := make([]byte, sz)
+	_, err := f.f.ReadAt(r, int64(off))
+	return r, err
+}
+
+func (f indexFileFromOS) Size() (uint32, error) {
+	fi, err := f.f.Stat()
+	if err != nil {
+		return 0, err
+	}
+
+	sz := fi.Size()
+
+	if sz >= maxUInt32 {
+		return 0, fmt.Errorf("overflow")
+	}
+
+	return uint32(sz), nil
+}
+
+func (f indexFileFromOS) Close() {
+	f.f.Close()
+}
+
+func (f indexFileFromOS) Name() string {
+	return f.f.Name()
+}
diff --git a/indexfile.go b/indexfile_unix.go
similarity index 63%
rename from indexfile.go
rename to indexfile_unix.go
index 2cb7941fd..fea4fae76 100644
--- a/indexfile.go
+++ b/indexfile_unix.go
@@ -12,24 +12,22 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build linux || darwin
+
 package zoekt
 
 import (
 	"fmt"
 	"log"
 	"os"
-	"runtime"
 
-	// cross-platform memory-mapped file package.
-	// Benchmarks the same speed as syscall/unix Mmap
-	// see https://github.com/peterguy/benchmark-mmap
-	mmap "github.com/edsrzf/mmap-go"
+	"golang.org/x/sys/unix"
 )
 
 type mmapedIndexFile struct {
 	name string
 	size uint32
-	data mmap.MMap
+	data []byte
 }
 
 func (f *mmapedIndexFile) Read(off, sz uint32) ([]byte, error) {
@@ -48,25 +46,11 @@ func (f *mmapedIndexFile) Size() (uint32, error) {
 }
 
 func (f *mmapedIndexFile) Close() {
-	if err := f.data.Unmap(); err != nil {
-		log.Printf("WARN failed to memory unmap %s: %v", f.name, err)
+	if err := unix.Munmap(f.data); err != nil {
+		log.Printf("WARN failed to Munmap %s: %v", f.name, err)
 	}
 }
 
-func bufferSize(f *mmapedIndexFile) int {
-	// On Unix/Linux, mmap likes to allocate memory in
-	// page-sized chunks, so round up to the OS page size.
-	// mmap will zero-fill the extra bytes.
-	// On Windows, the Windows API CreateFileMapping method
-	// requires a buffer the same size as the file.
-	bsize := int(f.size)
-	if runtime.GOOS != "windows" {
-		pagesize := os.Getpagesize() - 1
-		bsize = (bsize + pagesize) &^ pagesize
-	}
-	return bsize
-}
-
 // NewIndexFile returns a new index file. The index file takes
 // ownership of the passed in file, and may close it.
 func NewIndexFile(f *os.File) (IndexFile, error) {
@@ -86,10 +70,11 @@ func NewIndexFile(f *os.File) (IndexFile, error) {
 		size: uint32(sz),
 	}
 
-	r.data, err = mmap.MapRegion(f, bufferSize(r), mmap.RDONLY, 0, 0)
+	rounded := (r.size + 4095) &^ 4095
+	r.data, err = unix.Mmap(int(f.Fd()), 0, int(rounded), unix.PROT_READ, unix.MAP_SHARED)
 	if err != nil {
-		return nil, fmt.Errorf("NewIndexFile: unable to memory map %s: %w", f.Name(), err)
+		return nil, err
 	}
 
-	return r, nil
+	return r, err
 }