diff --git a/grub-core/commands/gptprio.c b/grub-core/commands/gptprio.c
index ce5840b4e..6b61bb56d 100644
--- a/grub-core/commands/gptprio.c
+++ b/grub-core/commands/gptprio.c
@@ -91,7 +91,7 @@ grub_find_next (const char *disk_name,
   if (!gpt)
     goto done;
 
-  if (!(gpt->status & GRUB_GPT_BOTH_VALID))
+  if ((gpt->status & GRUB_GPT_BOTH_VALID) != GRUB_GPT_BOTH_VALID)
     if (grub_gpt_repair (dev->disk, gpt))
       goto done;
 
diff --git a/grub-core/lib/gpt.c b/grub-core/lib/gpt.c
index 05d50bf3e..39c5f50ba 100644
--- a/grub-core/lib/gpt.c
+++ b/grub-core/lib/gpt.c
@@ -649,7 +649,7 @@ grub_gpt_write (grub_disk_t disk, grub_gpt_t gpt)
 {
   /* TODO: update/repair protective MBRs too.  */
 
-  if (!(gpt->status & GRUB_GPT_BOTH_VALID))
+  if ((gpt->status & GRUB_GPT_BOTH_VALID) != GRUB_GPT_BOTH_VALID)
     return grub_error (GRUB_ERR_BAD_PART_TABLE, "Invalid GPT data");
 
   grub_dprintf ("gpt", "writing primary GPT to %s\n", disk->name);
diff --git a/tests/gptprio_test.in b/tests/gptprio_test.in
index f4aea0dc9..c5cf0f3b7 100644
--- a/tests/gptprio_test.in
+++ b/tests/gptprio_test.in
@@ -66,8 +66,9 @@ prio_uuid[3]="1aa5a658-5b02-414d-9b71-f7e6c151f0cd"
 prio_uuid[4]="8aa0240d-98af-42b0-b32a-ccbe0572d62b"
 
 create_disk_image () {
+    size=$1
     rm -f "${img1}"
-    dd if=/dev/zero of="${img1}" bs=512 count=1 seek=100 status=none
+    dd if=/dev/zero of="${img1}" bs=512 count=1 seek=$((size - 1)) status=none
     ${sgdisk} \
         -n 1:0:+1 -c 1:ESP -t 1:ef00 \
         -n 2:0:+1 -c 2:A -t 2:"${prio_type}" -u 2:"${prio_uuid[2]}" \
@@ -76,6 +77,35 @@ create_disk_image () {
         "${img1}" >/dev/null
 }
 
+wipe_disk_area () {
+    sector=$1
+    size=$2
+    dd if=/dev/zero of="${img1}" bs=512 count=${size} seek=${sector} conv=notrunc status=none
+}
+
+is_zero () {
+    sector=$1
+    size=$2
+    cmp -s -i $((sector * 512)) -n $((size * 512)) /dev/zero "${img1}"
+}
+
+check_is_zero () {
+    sector=$1
+    size=$2
+    if ! is_zero "$@"; then
+        echo "$size sector(s) starting at $sector should be all zero"
+        exit 1
+    fi
+}
+
+check_not_zero () {
+    sector=$1
+    size=$2
+    if is_zero "$@"; then
+        echo "$size sector(s) starting at $sector should not be all zero"
+        exit 1
+    fi
+}
 
 fmt_prio () {
     priority=$(( ( $1 & 15 ) << 48 ))
@@ -93,10 +123,10 @@ set_prio () {
 check_prio () {
     part="$1"
     expect=$(fmt_prio $2 $3 $4)
-    result=$(LANG=C ${sgdisk} -i "${part}" "${img1}" \
+    result=$(LANG=C ${sgdisk} -i "${part}" "${img1}" 2>&1 \
             | awk '/^Attribute flags: / {print $3}')
     if [[ "${expect}" != "${result}" ]]; then
-        echo "Partition ${part} has attributes ${result}, not ${expect}" >&2
+        echo "Partition ${part} has attributes ${result:-??}, not ${expect}"
         exit 1
     fi
 }
@@ -133,6 +163,33 @@ create_disk_image 100
 set_prio 2 3 2 1
 check_prio 2 3 2 1
 
+# Check gptprio works without modifying the disk when no update is required.
+# Leaves any existing corruption as is, repairing in the OS is better.
+create_disk_image 100
+set_prio 2 1 0 1
+wipe_disk_area 99 1
+check_next 2 1 0 1
+check_is_zero 99 1
+
+create_disk_image 100
+set_prio 2 1 0 1
+wipe_disk_area 1 1
+check_next 2 1 0 1
+check_is_zero 1 1
+
+# When writes do need to be made go ahead and perform the repair.
+create_disk_image 100
+set_prio 2 1 1 0
+wipe_disk_area 99 1
+check_next 2 1 0 0
+check_not_zero 99 1
+
+create_disk_image 100
+set_prio 2 1 1 0
+wipe_disk_area 1 1
+check_next 2 1 0 0
+check_not_zero 1 1
+
 # Try two partitions before falling before falling back to a third
 create_disk_image 100
 set_prio 2 3 3 0
diff --git a/tests/gptrepair_test.in b/tests/gptrepair_test.in
index 80b2de633..805dc171a 100644
--- a/tests/gptrepair_test.in
+++ b/tests/gptrepair_test.in
@@ -53,7 +53,7 @@ case "${grub_modinfo_target_cpu}-${grub_modinfo_platform}" in
 esac
 img1="`mktemp "${TMPDIR:-/tmp}/tmp.XXXXXXXXXX"`" || exit 1
 img2="`mktemp "${TMPDIR:-/tmp}/tmp.XXXXXXXXXX"`" || exit 1
-trap "rm -f '${img1}' '${ing2}'" EXIT
+trap "rm -f '${img1}' '${img2}'" EXIT
 
 create_disk_image () {
     size=$1