diff --git a/CHANGELOG.md b/CHANGELOG.md
index 957b86c..c2f31a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
  - New gitlab #7: New style patterns, to be in line with CalVer.org
      - Better support for week numbering.
      - Better support for optional parts.
+     - New: Start `BUILD` parts at `1000` to avoid leading zero truncation.
  - New gitlab #10: `--pin-date` to keep date parts unchanged, and only increment non-date parts.
  - Fix gitlab #8: Push tags only pushed tags, not actual commit.
  - Fix gitlab #9: Make commit message configurable.
diff --git a/src/pycalver2/version.py b/src/pycalver2/version.py
index e705293..5a6bc5a 100644
--- a/src/pycalver2/version.py
+++ b/src/pycalver2/version.py
@@ -486,7 +486,12 @@ def incr(
     else:
         logger.warning(f"Version appears to be from the future '{old_version}'")
 
-    cur_vinfo = cur_vinfo._replace(bid=lexid.incr(cur_vinfo.bid))
+    _bid = cur_vinfo.bid
+    if int(_bid) < 1000:
+        # prevent truncation of leading zeros
+        _bid = str(int(_bid) + 1000)
+
+    cur_vinfo = cur_vinfo._replace(bid=lexid.incr(_bid))
 
     if major:
         cur_vinfo = cur_vinfo._replace(major=cur_vinfo.major + 1, minor=0, patch=0)