diff --git a/scripts/diffcheck.sh b/scripts/diffcheck.sh
index aa9f557cf2..1bc39332f4 100755
--- a/scripts/diffcheck.sh
+++ b/scripts/diffcheck.sh
@@ -1,10 +1,27 @@
 #!/bin/bash
 
+set -euo pipefail
+
 scripts/buildtable.pl >/tmp/table.mediawiki 2> /dev/null
 diff README.mediawiki /tmp/table.mediawiki | grep '^[<>] |' >/tmp/after.diff || true
-if git checkout HEAD^ && scripts/buildtable.pl >/tmp/table.mediawiki 2>/dev/null; then
+
+orig_branch=$(git symbolic-ref --short HEAD 2>/dev/null || true)
+orig_head=$(git rev-parse HEAD)
+
+cleanup() {
+    if [[ -n "$orig_branch" ]]; then
+        git checkout "$orig_branch" >/dev/null 2>&1 || git checkout "$orig_head" >/dev/null 2>&1
+    else
+        git checkout "$orig_head" >/dev/null 2>&1 || true
+    fi
+}
+trap cleanup EXIT
+
+if git checkout HEAD^ >/dev/null 2>&1; then
+    trap 'cleanup; exit 1' INT TERM HUP
+    scripts/buildtable.pl >/tmp/table.mediawiki 2>/dev/null
     diff README.mediawiki /tmp/table.mediawiki | grep '^[<>] |' >/tmp/before.diff || true
-    newdiff=$(diff -s /tmp/before.diff /tmp/after.diff -u | grep '^+')
+    newdiff=$(diff -s /tmp/before.diff /tmp/after.diff -u | grep '^[+]')
     if [ -n "$newdiff" ]; then
         echo "$newdiff"
         exit 1