diff --git a/disk-image.c b/disk-image.c
index 9deaf45..595d407 100644
--- a/disk-image.c
+++ b/disk-image.c
@@ -13,7 +13,7 @@
 #include <unistd.h>
 #include <fcntl.h>
 
-struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_operations *ops)
+struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_operations *ops, bool readonly)
 {
 	struct disk_image *self;
 
@@ -24,6 +24,12 @@ struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_oper
 	self->fd	= fd;
 	self->size	= size;
 	self->ops	= ops;
+	if (readonly) {
+		self->priv = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_NORESERVE, fd, 0);
+		if (self->priv == MAP_FAILED)
+			die("mmap() failed");
+	} else
+		self->priv = MAP_FAILED;
 
 	return self;
 }
@@ -54,31 +60,60 @@ static int raw_image__write_sector(struct disk_image *self, uint64_t sector, voi
 	return 0;
 }
 
+static int raw_image__read_sector_ro_mmap(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)
+{
+	uint64_t offset = sector << SECTOR_SHIFT;
+
+	if (offset + dst_len > self->size)
+		return -1;
+
+	memcpy(dst, self->priv + offset, dst_len);
+
+	return 0;
+}
+
+static int raw_image__write_sector_ro_mmap(struct disk_image *self, uint64_t sector, void *src, uint32_t src_len)
+{
+	uint64_t offset = sector << SECTOR_SHIFT;
+
+	if (offset + src_len > self->size)
+		return -1;
+
+	memcpy(self->priv + offset, src, src_len);
+
+	return 0;
+}
+
 static struct disk_image_operations raw_image_ops = {
 	.read_sector		= raw_image__read_sector,
 	.write_sector		= raw_image__write_sector,
 };
 
-static struct disk_image *raw_image__probe(int fd)
+static struct disk_image_operations raw_image_ro_mmap_ops = {
+	.read_sector		= raw_image__read_sector_ro_mmap,
+	.write_sector		= raw_image__write_sector_ro_mmap,
+};
+
+static struct disk_image *raw_image__probe(int fd, bool readonly)
 {
 	struct stat st;
 
 	if (fstat(fd, &st) < 0)
 		return NULL;
 
-	return disk_image__new(fd, st.st_size, &raw_image_ops);
+	return disk_image__new(fd, st.st_size, readonly ? &raw_image_ro_mmap_ops : &raw_image_ops, readonly);
 }
 
-struct disk_image *disk_image__open(const char *filename)
+struct disk_image *disk_image__open(const char *filename, bool readonly)
 {
 	struct disk_image *self;
 	int fd;
 
-	fd		= open(filename, O_RDWR);
+	fd		= open(filename, readonly ? O_RDONLY : O_RDWR);
 	if (fd < 0)
 		return NULL;
 
-	self = raw_image__probe(fd);
+	self = raw_image__probe(fd, readonly);
 	if (self)
 		return self;
 
@@ -94,6 +129,9 @@ void disk_image__close(struct disk_image *self)
 	if (!self)
 		return;
 
+	if (self->priv != MAP_FAILED)
+		munmap(self->priv, self->size);
+
 	if (self->ops->close)
 		self->ops->close(self);
 
diff --git a/include/kvm/disk-image.h b/include/kvm/disk-image.h
index df0a15d..91240c2 100644
--- a/include/kvm/disk-image.h
+++ b/include/kvm/disk-image.h
@@ -2,6 +2,7 @@
 #define KVM__DISK_IMAGE_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
 #define SECTOR_SHIFT		9
 #define SECTOR_SIZE		(1UL << SECTOR_SHIFT)
@@ -21,8 +22,8 @@ struct disk_image {
 	void				*priv;
 };
 
-struct disk_image *disk_image__open(const char *filename);
-struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_operations *ops);
+struct disk_image *disk_image__open(const char *filename, bool readonly);
+struct disk_image *disk_image__new(int fd, uint64_t size, struct disk_image_operations *ops, bool readonly);
 void disk_image__close(struct disk_image *self);
 
 static inline int disk_image__read_sector(struct disk_image *self, uint64_t sector, void *dst, uint32_t dst_len)
diff --git a/kvm-run.c b/kvm-run.c
index 8f6ebdc..ba02172 100644
--- a/kvm-run.c
+++ b/kvm-run.c
@@ -61,6 +61,7 @@ static const char *image_filename;
 static const char *console;
 static const char *kvm_dev;
 static bool single_step;
+static bool readonly_image;
 extern bool ioport_debug;
 extern int  active_console;
 
@@ -80,6 +81,8 @@ static const struct option options[] = {
 	OPT_STRING('k', "kernel", &kernel_filename, "kernel",
 			"Kernel to boot in virtual machine"),
 	OPT_STRING('i', "image", &image_filename, "image", "Disk image"),
+	OPT_BOOLEAN('\0', "readonly", &readonly_image,
+			"Don't write changes back to disk image"),
 	OPT_STRING('d', "kvm-dev", &kvm_dev, "kvm-dev", "KVM device file"),
 	OPT_BOOLEAN('s', "single-step", &single_step,
 			"Enable single stepping"),
@@ -183,7 +186,7 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 	kvm = kvm__init(kvm_dev, ram_size);
 
 	if (image_filename) {
-		kvm->disk_image	= disk_image__open(image_filename);
+		kvm->disk_image	= disk_image__open(image_filename, readonly_image);
 		if (!kvm->disk_image)
 			die("unable to load disk image %s", image_filename);
 	}