diff --git a/clang/tools/clang-format/clang-format-diff.py b/clang/tools/clang-format/clang-format-diff.py
index c82b41e8bd03..e1d635fc85ff 100755
--- a/clang/tools/clang-format/clang-format-diff.py
+++ b/clang/tools/clang-format/clang-format-diff.py
@@ -102,9 +102,9 @@ def main():
     filename = None
     lines_by_file = {}
     for line in sys.stdin:
-        match = re.search(r"^\+\+\+\ (.*?/){%s}(\S*)" % args.p, line)
+        match = re.search(r"^\+\+\+\s+(?:.*?/){%s}(.+)$" % args.p, line)
         if match:
-            filename = match.group(2)
+            filename = match.group(1).strip()
         if filename is None:
             continue