diff --git a/utils/dbfixup.py b/utils/dbfixup.py
index 976891e7..1d7ce43c 100644
--- a/utils/dbfixup.py
+++ b/utils/dbfixup.py
@@ -28,6 +28,30 @@ def add_zero_bits(tile_type):
         for line in sorted(new_lines):
             print(line, file=f)
 
+def update_mask(mask_db, *src_dbs):
+    bits = set()
+    with open("%s/%s/mask_%s.db" % (os.getenv("XRAY_DATABASE_DIR"), os.getenv("XRAY_DATABASE"), mask_db), "r") as f:
+        for line in f:
+            line = line.split()
+            assert len(line) == 2
+            assert line[0] == "bit"
+            bits.add(line[1])
+    for src_db in src_dbs:
+        with open("%s/%s/segbits_%s.db" % (os.getenv("XRAY_DATABASE_DIR"), os.getenv("XRAY_DATABASE"), src_db), "r") as f:
+            for line in f:
+                line = line.split()
+                for bit in line[1:]:
+                    if bit[0] != "!":
+                        bits.add(bit)
+    with open("%s/%s/mask_%s.db" % (os.getenv("XRAY_DATABASE_DIR"), os.getenv("XRAY_DATABASE"), mask_db), "w") as f:
+        for bit in sorted(bits):
+            print("bit %s" % bit, file=f)
+
 add_zero_bits("int_l")
 add_zero_bits("int_r")
 
+update_mask("clbll_l", "clbll_l", "int_l")
+update_mask("clbll_r", "clbll_r", "int_r")
+update_mask("clblm_l", "clblm_l", "int_l")
+update_mask("clblm_r", "clblm_r", "int_r")
+