diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c
index 0bbe9ba..d26e3d7 100644
--- a/tools/kvm/kvm.c
+++ b/tools/kvm/kvm.c
@@ -351,10 +351,11 @@ struct kvm *kvm__init(const char *kvm_dev, u64 ram_size, const char *name)
 /* RFC 1952 */
 #define GZIP_ID1		0x1f
 #define GZIP_ID2		0x8b
-
+#define CPIO_MAGIC		"0707"
+/* initrd may be gzipped, or a plain cpio */
 static bool initrd_check(int fd)
 {
-	unsigned char id[2];
+	unsigned char id[4];
 
 	if (read_in_full(fd, id, ARRAY_SIZE(id)) < 0)
 		return false;
@@ -362,7 +363,8 @@ static bool initrd_check(int fd)
 	if (lseek(fd, 0, SEEK_SET) < 0)
 		die_perror("lseek");
 
-	return id[0] == GZIP_ID1 && id[1] == GZIP_ID2;
+	return (id[0] == GZIP_ID1 && id[1] == GZIP_ID2) ||
+		!memcmp(id, CPIO_MAGIC, 4);
 }
 
 bool kvm__load_kernel(struct kvm *kvm, const char *kernel_filename,