diff --git a/go.mod b/go.mod
index 7db26699..bba9944c 100644
--- a/go.mod
+++ b/go.mod
@@ -14,4 +14,4 @@ require (
 
 retract v0.4.0 // tagged from the wrong branch
 
-replace github.com/tetratelabs/wazero => github.com/ncruces/wazero v0.0.0-20240406121256-0283488c26c8
+replace github.com/tetratelabs/wazero => github.com/ncruces/wazero v0.0.0-20240409112346-f2be6da37a3d
diff --git a/go.sum b/go.sum
index 8a4222dc..b7cf7d7c 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
 github.com/ncruces/julianday v1.0.0 h1:fH0OKwa7NWvniGQtxdJRxAgkBMolni2BjDHaWTxqt7M=
 github.com/ncruces/julianday v1.0.0/go.mod h1:Dusn2KvZrrovOMJuOt0TNXL6tB7U2E8kvza5fFc9G7g=
-github.com/ncruces/wazero v0.0.0-20240406121256-0283488c26c8 h1:Xix9dlK5BpStboVxuRS/DNdwE2YqGROwf7gfqHJn/Mk=
-github.com/ncruces/wazero v0.0.0-20240406121256-0283488c26c8/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
+github.com/ncruces/wazero v0.0.0-20240409112346-f2be6da37a3d h1:t3S5uhR50fDxrCgoMLcVDFo2jpYdKjq5VWbXFUMHv0w=
+github.com/ncruces/wazero v0.0.0-20240409112346-f2be6da37a3d/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
 github.com/psanford/httpreadat v0.1.0 h1:VleW1HS2zO7/4c7c7zNl33fO6oYACSagjJIyMIwZLUE=
 github.com/psanford/httpreadat v0.1.0/go.mod h1:Zg7P+TlBm3bYbyHTKv/EdtSJZn3qwbPwpfZ/I9GKCRE=
 golang.org/x/crypto v0.22.0 h1:g1v0xeRhjcugydODzvb3mEM9SQ0HGp9s/nh3COQ/C30=
diff --git a/go.work.sum b/go.work.sum
index 44186537..e1395588 100644
--- a/go.work.sum
+++ b/go.work.sum
@@ -1,5 +1,5 @@
-github.com/ncruces/wazero v0.0.0-20240406121256-0283488c26c8 h1:Xix9dlK5BpStboVxuRS/DNdwE2YqGROwf7gfqHJn/Mk=
-github.com/ncruces/wazero v0.0.0-20240406121256-0283488c26c8/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
+github.com/ncruces/wazero v0.0.0-20240409112346-f2be6da37a3d h1:t3S5uhR50fDxrCgoMLcVDFo2jpYdKjq5VWbXFUMHv0w=
+github.com/ncruces/wazero v0.0.0-20240409112346-f2be6da37a3d/go.mod h1:ytl6Zuh20R/eROuyDaGPkp82O9C/DJfXAwJfQ3X6/7Y=
 golang.org/x/mod v0.8.0 h1:LUYupSeNrTNCGzR/hVBk2NHZO4hXcVaW1k4Qx7rjPx8=
 golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
 golang.org/x/net v0.21.0 h1:AQyQV4dYCvJ7vGmJyKki9+PBdyvhkSd8EIx/qb0AYv4=
diff --git a/internal/util/alloc.go b/internal/util/alloc.go
index eccfb6d5..9601dcf0 100644
--- a/internal/util/alloc.go
+++ b/internal/util/alloc.go
@@ -1,53 +1,68 @@
-//go:build (linux || darwin) && (amd64 || arm64)
+//go:build unix
 
 package util
 
 import (
 	"math"
-	"syscall"
-)
 
-type MmapedMemoryAllocator []byte
+	"github.com/tetratelabs/wazero/experimental"
+	"golang.org/x/sys/unix"
+)
 
-func (m *MmapedMemoryAllocator) Make(min, cap, max uint64) []byte {
+func mmappedAllocator(min, cap, max uint64) experimental.MemoryBuffer {
 	if max > math.MaxInt {
 		// This ensures int(max) overflows to a negative value,
-		// and syscall.Mmap returns EINVAL.
+		// and unix.Mmap returns EINVAL.
 		max = math.MaxUint64
 	}
 	// Reserve the full max bytes of address space, to ensure we don't need to move it.
 	// A protected, private, anonymous mapping should not commit memory.
-	b, err := syscall.Mmap(-1, 0, int(max), syscall.PROT_NONE, syscall.MAP_PRIVATE|syscall.MAP_ANON)
+	b, err := unix.Mmap(-1, 0, int(max), unix.PROT_NONE, unix.MAP_PRIVATE|unix.MAP_ANON)
 	if err != nil {
 		panic(err)
 	}
-	// Commit the initial min bytes of memory.
-	err = syscall.Mprotect(b[:min], syscall.PROT_READ|syscall.PROT_WRITE)
+	// Commit the initial cap bytes of memory.
+	err = unix.Mprotect(b[:cap], unix.PROT_READ|unix.PROT_WRITE)
 	if err != nil {
-		syscall.Munmap(b)
+		unix.Munmap(b)
 		panic(err)
 	}
-	b = b[:min]
-	*m = b
-	return b
+	return &mmappedBuffer{
+		buf: b[:cap],
+		cur: min,
+	}
+}
+
+// The slice covers the entire mmapped memory:
+//   - len(buf) is the already committed memory,
+//   - cap(buf) is the reserved address space,
+//   - cur is the already requested size.
+type mmappedBuffer struct {
+	buf []byte
+	cur uint64
+}
+
+func (m *mmappedBuffer) Buffer() []byte {
+	// Limit capacity because bytes beyond len(m.buf)
+	// have not yet been committed.
+	return m.buf[:m.cur:len(m.buf)]
 }
 
-func (m *MmapedMemoryAllocator) Grow(size uint64) []byte {
-	b := *m
+func (m *mmappedBuffer) Grow(size uint64) []byte {
 	// Commit additional memory up to size bytes.
-	err := syscall.Mprotect(b[len(b):size], syscall.PROT_READ|syscall.PROT_WRITE)
+	err := unix.Mprotect(m.buf[len(m.buf):size], unix.PROT_READ|unix.PROT_WRITE)
 	if err != nil {
 		panic(err)
 	}
-	b = b[:size]
-	*m = b
-	return b
+	m.buf = m.buf[:size]
+	m.cur = size
+	return m.Buffer()
 }
 
-func (m *MmapedMemoryAllocator) Free() {
-	err := syscall.Munmap(*m)
+func (m *mmappedBuffer) Free() {
+	err := unix.Munmap(m.buf)
 	if err != nil {
 		panic(err)
 	}
-	*m = nil
+	m.buf = nil
 }
diff --git a/internal/util/handle.go b/internal/util/handle.go
index cf4359c5..4584324c 100644
--- a/internal/util/handle.go
+++ b/internal/util/handle.go
@@ -10,12 +10,14 @@ type handleState struct {
 	holes   int
 }
 
-func (s *handleState) close() {
+func (s *handleState) CloseNotify(ctx context.Context, exitCode uint32) {
 	for _, h := range s.handles {
 		if c, ok := h.(io.Closer); ok {
 			c.Close()
 		}
 	}
+	s.handles = nil
+	s.holes = 0
 }
 
 func GetHandle(ctx context.Context, id uint32) any {
diff --git a/internal/util/mmap.go b/internal/util/mmap.go
index 17ab0d60..c2216940 100644
--- a/internal/util/mmap.go
+++ b/internal/util/mmap.go
@@ -19,7 +19,7 @@ type mmapState struct {
 
 func (s *mmapState) init(ctx context.Context, enabled bool) context.Context {
 	if s.enabled = enabled; enabled {
-		return experimental.WithMemoryAllocator(ctx, &MmapedMemoryAllocator{})
+		return experimental.WithMemoryAllocator(ctx, mmappedAllocator)
 	}
 	return ctx
 }
diff --git a/internal/util/module.go b/internal/util/module.go
index 9d5d153b..0db93bbb 100644
--- a/internal/util/module.go
+++ b/internal/util/module.go
@@ -19,8 +19,3 @@ func NewContext(ctx context.Context, mappableMemory bool) context.Context {
 	ctx = state.mmapState.init(ctx, mappableMemory)
 	return ctx
 }
-
-func (s *moduleState) CloseNotify(ctx context.Context, exitCode uint32) {
-	s.handleState.close()
-	*s = moduleState{}
-}