diff --git a/futility/futility.h b/futility/futility.h
index f063575..f5f6877 100644
--- a/futility/futility.h
+++ b/futility/futility.h
@@ -108,6 +108,9 @@
 int futil_valid_gbb_header(GoogleBinaryBlockHeader *gbb, uint32_t len,
 			   uint32_t *maxlen);
 
+/* Sets the HWID string field inside a GBB header. */
+int futil_set_gbb_hwid(struct vb2_gbb_header *gbb, const char *hwid);
+
 /* For GBB v1.2 and later, update the hwid_digest */
 void update_hwid_digest(GoogleBinaryBlockHeader *gbb);
 
diff --git a/futility/misc.c b/futility/misc.c
index 703033c..af291a4 100644
--- a/futility/misc.c
+++ b/futility/misc.c
@@ -4,6 +4,7 @@
  * found in the LICENSE file.
  */
 
+#include <assert.h>
 #include <errno.h>
 #ifndef HAVE_MACOS
 #include <linux/fs.h>		/* For BLKGETSIZE64 */
@@ -166,6 +167,7 @@
 	return is_valid;
 }
 
+/* Deprecated. Use futil_set_gbb_hwid in future. */
 /* For GBB v1.2 and later, update the hwid_digest field. */
 void update_hwid_digest(GoogleBinaryBlockHeader *gbb)
 {
@@ -181,6 +183,29 @@
 			  gbb->hwid_digest, sizeof(gbb->hwid_digest));
 }
 
+/* Sets the HWID string field inside a GBB header. */
+int futil_set_gbb_hwid(struct vb2_gbb_header *gbb, const char *hwid)
+{
+	uint8_t *to = (uint8_t *)gbb + gbb->hwid_offset;
+	size_t len;
+
+	assert(hwid);
+	len = strlen(hwid);
+	if (len >= gbb->hwid_size)
+		return -1;
+
+	/* Zero whole area so we won't have garbage after NUL. */
+	memset(to, 0, gbb->hwid_size);
+	memcpy(to, hwid, len);
+
+	/* major_version starts from 1 and digest must be updated since v1.2. */
+	if (gbb->major_version == 1 && gbb->minor_version < 2)
+		return 0;
+
+	return vb2_digest_buffer(to, len, VB2_HASH_SHA256, gbb->hwid_digest,
+				 sizeof(gbb->hwid_digest));
+}
+
 /*
  * TODO: All sorts of race conditions likely here, and everywhere this is used.
  * Do we care? If so, fix it.
diff --git a/futility/updater.c b/futility/updater.c
index d16fe38..d1352ef 100644
--- a/futility/updater.c
+++ b/futility/updater.c
@@ -972,8 +972,6 @@
 			struct firmware_image *image_to,
 			int preserve_flags)
 {
-	int len;
-	uint8_t *hwid_to, *hwid_from;
 	const struct vb2_gbb_header *gbb_from;
 	struct vb2_gbb_header *gbb_to;
 
@@ -988,18 +986,9 @@
 	if (preserve_flags)
 		gbb_to->flags = gbb_from->flags;
 
-	hwid_to = (uint8_t *)gbb_to + gbb_to->hwid_offset;
-	hwid_from = (uint8_t *)gbb_from + gbb_from->hwid_offset;
-
 	/* Preserve HWID. */
-	len = strlen((const char *)hwid_from);
-	if (len >= gbb_to->hwid_size)
-		return -1;
-
-	/* Zero whole area so we won't have garbage after NUL. */
-	memset(hwid_to, 0, gbb_to->hwid_size);
-	memcpy(hwid_to, hwid_from, len);
-	return 0;
+	return futil_set_gbb_hwid(
+			gbb_to, (const char *)gbb_from + gbb_from->hwid_offset);
 }
 
 /*
diff --git a/tests/futility/test_update.sh b/tests/futility/test_update.sh
index c72a105..302bf26 100755
--- a/tests/futility/test_update.sh
+++ b/tests/futility/test_update.sh
@@ -91,6 +91,17 @@
 cp -f "${FROM_IMAGE}" "${FROM_IMAGE}.large"
 truncate -s $((8388608 * 2)) "${FROM_IMAGE}.large"
 
+# Create GBB v1.2 images (for checking digest)
+GBB_OUTPUT="$("${FUTILITY}" gbb --digest "${TO_IMAGE}")"
+[ "${GBB_OUTPUT}" = "digest: <none>" ]
+TO_IMAGE_GBB12="${TO_IMAGE}.gbb12"
+HWID_DIGEST="adf64d2a434b610506153da42440b0b498d7369c0e98b629ede65eb59f4784fa"
+cp -f "${TO_IMAGE}" "${TO_IMAGE_GBB12}"
+patch_file "${TO_IMAGE_GBB12}" GBB 6 "\x02"
+"${FUTILITY}" gbb -s --hwid="${TO_HWID}" "${TO_IMAGE_GBB12}"
+GBB_OUTPUT="$("${FUTILITY}" gbb --digest "${TO_IMAGE_GBB12}")"
+[ "${GBB_OUTPUT}" = "digest: ${HWID_DIGEST}   valid" ]
+
 # Generate expected results.
 cp -f "${TO_IMAGE}" "${TMP}.expected.full"
 cp -f "${FROM_IMAGE}" "${TMP}.expected.rw"
@@ -112,6 +123,9 @@
 	RW_SECTION_B:${TMP}.to/RW_SECTION_B
 "${FUTILITY}" load_fmap "${TMP}.expected.legacy" \
 	RW_LEGACY:${TMP}.to/RW_LEGACY
+cp -f "${TMP}.expected.full" "${TMP}.expected.full.gbb12"
+patch_file "${TMP}.expected.full.gbb12" GBB 6 "\x02"
+"${FUTILITY}" gbb -s --hwid="${FROM_HWID}" "${TMP}.expected.full.gbb12"
 cp -f "${TMP}.expected.full" "${TMP}.expected.full.gbb0"
 "${FUTILITY}" gbb -s --flags=0 "${TMP}.expected.full.gbb0"
 cp -f "${FROM_IMAGE}" "${FROM_IMAGE}.gbb0"
@@ -187,6 +201,10 @@
 	-i "${TO_IMAGE}" --wp=0 --sys_props 0,0x10001,1 \
 	--host_only --ec_image non-exist.bin --pd_image non_exist.bin
 
+test_update "Full update (GBB1.2 hwid digest)" \
+	"${FROM_IMAGE}" "${TMP}.expected.full.gbb12" \
+	-i "${TO_IMAGE_GBB12}" --wp=0 --sys_props 0,0x10001,1
+
 # Test RW-only update.
 test_update "RW update" \
 	"${FROM_IMAGE}" "${TMP}.expected.rw" \