diff --git a/jni/magiskboot/magiskboot.h b/jni/magiskboot/magiskboot.h
index 00930b1aa..c58378ccb 100644
--- a/jni/magiskboot/magiskboot.h
+++ b/jni/magiskboot/magiskboot.h
@@ -94,7 +94,6 @@ extern unsigned char *kernel, *ramdisk, *second, *dtb, *extra;
 extern boot_img_hdr hdr;
 extern file_t boot_type, ramdisk_type, dtb_type;
 extern int mtk_kernel, mtk_ramdisk;
-extern int zero;
 
 // Main entries
 void unpack(const char *image);
@@ -119,6 +118,7 @@ void decomp_file(char *from, const char *to);
 void mmap_ro(const char *filename, unsigned char **buf, size_t *size);
 void mmap_rw(const char *filename, unsigned char **buf, size_t *size);
 file_t check_type(const unsigned char *buf);
+void write_zero(int fd, size_t size);
 void mem_align(size_t *pos, size_t align);
 void file_align(int fd, size_t align, int out);
 int open_new(const char *filename);
diff --git a/jni/magiskboot/repack.c b/jni/magiskboot/repack.c
index fac089159..c76805fb5 100644
--- a/jni/magiskboot/repack.c
+++ b/jni/magiskboot/repack.c
@@ -21,9 +21,6 @@ static void restore_buf(int fd, const void *buf, size_t size) {
 }
 
 void repack(const char* orig_image, const char* out_image) {
-	zero = open("/dev/zero", O_RDONLY);
-	if (zero < 0) error(1, "Cannot open /dev/zero");
-
 	size_t size;
 	unsigned char *orig;
 	char name[PATH_MAX];
@@ -51,12 +48,12 @@ void repack(const char* orig_image, const char* out_image) {
 	hdr.dt_size = 0;
 
 	// Skip a page for header
-	sendfile(fd, zero, NULL, hdr.page_size);
+	write_zero(fd, hdr.page_size);
 
 	// Restore kernel
 	if (mtk_kernel) {
 		mtk_kernel_off = lseek(fd, 0, SEEK_CUR);
-		sendfile(fd, zero, NULL, 512);
+		write_zero(fd, 512);
 		memcpy(&mtk_kernel_hdr, kernel, sizeof(mtk_kernel_hdr));
 	}
 	hdr.kernel_size = restore(KERNEL_FILE, fd);
@@ -65,7 +62,7 @@ void repack(const char* orig_image, const char* out_image) {
 	// Restore ramdisk
 	if (mtk_ramdisk) {
 		mtk_ramdisk_off = lseek(fd, 0, SEEK_CUR);
-		sendfile(fd, zero, NULL, 512);
+		write_zero(fd, 512);
 		memcpy(&mtk_ramdisk_hdr, ramdisk, sizeof(mtk_ramdisk_hdr));
 	}
 	if (access(RAMDISK_FILE, R_OK) == 0) {
diff --git a/jni/magiskboot/utils.c b/jni/magiskboot/utils.c
index 514fe917e..18c48ea3e 100644
--- a/jni/magiskboot/utils.c
+++ b/jni/magiskboot/utils.c
@@ -3,7 +3,6 @@
 
 char *SUP_EXT_LIST[SUP_NUM] = { "gz", "xz", "lzma", "bz2", "lz4" };
 file_t SUP_TYPE_LIST[SUP_NUM] = { GZIP, XZ, LZMA, BZIP2, LZ4 };
-int zero = -1;
 
 void mmap_ro(const char *filename, unsigned char **buf, size_t *size) {
 	int fd = open(filename, O_RDONLY);
@@ -56,6 +55,12 @@ file_t check_type(const unsigned char *buf) {
 	}
 }
 
+void write_zero(int fd, size_t size) {
+	size_t pos = lseek(fd, 0, SEEK_CUR);
+	ftruncate(fd, pos + size);
+	lseek(fd, pos + size, SEEK_SET);
+}
+
 void mem_align(size_t *pos, size_t align) {
 	size_t mask = align - 1;
 	if (*pos & mask) {
@@ -70,11 +75,7 @@ void file_align(int fd, size_t align, int out) {
 	if (pos & mask) {
 		off = align - (pos & mask);
 		if (out) {
-			if (zero < 0) {
-				zero = open("/dev/zero", O_RDONLY);
-				if (zero < 0) error(1, "Cannot open /dev/zero");
-			}
-			sendfile(fd, zero, NULL, off);
+			write_zero(fd, off);
 		} else {
 			lseek(fd, pos + off, SEEK_SET);
 		}