diff --git a/tools/lib/python/kdoc/kdoc_re.py b/tools/lib/python/kdoc/kdoc_re.py
index 774dd747ecb0..6c44fcce0415 100644
--- a/tools/lib/python/kdoc/kdoc_re.py
+++ b/tools/lib/python/kdoc/kdoc_re.py
@@ -269,7 +269,7 @@ class NestedMatch:
             out += new_sub
 
             # Drop end ';' if any
-            if line[pos] == ';':
+            if pos < len(line) and line[pos] == ';':
                 pos += 1
 
             cur_pos = pos