diff --git a/tagger b/tagger
index 3dc5991..d44dbc8 100755
--- a/tagger
+++ b/tagger
@@ -7,17 +7,28 @@ import subprocess
 
 ap = argparse.ArgumentParser()
 ap.add_argument("--fullyear", action="store_true")
+ap.add_argument("--prefix", default="r")
+ap.add_argument("--noop", action="store_true")
 args = ap.parse_args()
 
 subprocess.run(["git", "pull"])
 result = subprocess.run(["git", "log", "--pretty=format:%H %D", "--date-order"], stdout=subprocess.PIPE, universal_newlines=True)
 found_tags = set()
 need_tag = False
+max_major = 0
 for ln in result.stdout.split("\n"):
 
     m = re.match(r"[0-9a-f]+ .*\btag: ([-a-z0-9._]+)", ln)
     if m:
-        found_tags.add(m.group(1))
+        tag = m.group(1)
+        if tag.startswith(args.prefix):
+            found_tags.add(tag)
+            try:
+                major = int(tag[len(args.prefix):].split(".")[0])
+                max_major = max(max_major, major)
+            except ValueError:
+                # Silently ignore tags which don't start with a number
+                pass
 
     if not found_tags:
         need_tag = True
@@ -26,16 +37,22 @@ print(need_tag, found_tags)
 if need_tag:
     today = datetime.date.today()
     if args.fullyear:
-        tag = today.strftime("r%Y.%m.%d")
+        tag = args.prefix + today.strftime("%Y.%m.%d")
     else:
-        tag = today.strftime("r%y.%m.%d")
+        year = today.year
+        for m in (10, 100, 1000, 10000):
+            if year % m >= max_major:
+                major = str(year % m)
+                break
+        tag = args.prefix + major + today.strftime(".%m.%d")
     if tag in found_tags:
         inc = 1
         while f"{tag}.{inc}" in found_tags:
             inc += 1
         tag = f"{tag}.{inc}"
     print(tag)
-    subprocess.run(["git", "tag", "-a", tag, "-m", "auto-tagged"])
-    subprocess.run(["git", "push", "--tags"])
+    if not args.noop:
+        subprocess.run(["git", "tag", "-a", tag, "-m", "auto-tagged"])
+        subprocess.run(["git", "push", "--tags"])
 
 # vim: expandtab sw=4