diff --git a/prjxray/util.py b/prjxray/util.py
index 390e0c81..3fa592c5 100644
--- a/prjxray/util.py
+++ b/prjxray/util.py
@@ -71,3 +71,23 @@ def db_root_arg(parser):
         db_root_kwargs['required'] = False
         db_root_kwargs['default'] = os.path.join(database_dir, database)
     parser.add_argument('--db-root', help="Database root.", **db_root_kwargs)
+
+
+def parse_db_line(line):
+    parts = line.split()
+    # Ex: CLBLL_L.SLICEL_X0.AMUX.A5Q
+    assert len(parts), "Empty line"
+    tag = parts[0]
+    assert re.match(r'[A-Z0-9_.]+',
+                    tag), "Invalid tag name: %s, line: %s" % (tag, line)
+    orig_bits = line.replace(tag + " ", "")
+    # <0 candidates> etc
+    if "<" in orig_bits:
+        return tag, set(), orig_bits
+
+    # Ex: !30_06 !30_08 !30_11 30_07
+    bits = frozenset(parts[1:])
+    for bit in bits:
+        assert re.match(
+            r'[!]*[0-9][0-9]_[0-9][0-9]', bit), "Invalid bit: %s" % bit
+    return tag, bits, None
diff --git a/utils/dbfixup.py b/utils/dbfixup.py
index 1dd5f872..9d13bb07 100755
--- a/utils/dbfixup.py
+++ b/utils/dbfixup.py
@@ -17,20 +17,6 @@ clb_int_zero_db = [
 ]
 
 
-def parse_line(line):
-    parts = line.split()
-    # Ex: CLBLL_L.SLICEL_X0.AMUX.A5Q
-    tag = parts[0]
-    orig_bits = line.replace(tag + " ", "")
-    # <0 candidates> etc
-    if "<" in orig_bits:
-        return tag, set(), orig_bits
-
-    # Ex: !30_06 !30_08 !30_11 30_07
-    bits = set(parts[1:])
-    return tag, bits, None
-
-
 def zero_range(bits, wordmin, wordmax):
     """
     If any bits occur wordmin <= word <= wordmax,
@@ -134,7 +120,7 @@ def add_zero_bits(fn_in, fn_out, zero_db, clb_int=False, verbose=False):
             if line == llast:
                 continue
 
-            tag, bits, mode = parse_line(line)
+            tag, bits, mode = util.parse_db_line(line)
             assert mode not in (
                 "<const0>",
                 "<const1>"), "Entries must be resolved. line: %s" % (line, )