diff --git a/tools/ci_set_matrix.py b/tools/ci_set_matrix.py
index e8a7c95656..efb4427e7e 100644
--- a/tools/ci_set_matrix.py
+++ b/tools/ci_set_matrix.py
@@ -68,8 +68,8 @@ def set_boards_to_build(build_all):
 
     if not build_all:
         boards_to_build = set()
-        board_pattern = re.compile(r"^ports\/[^/]+\/boards\/([^/]+)\/")
-        port_pattern = re.compile(r"^ports\/([^/]+)\/")
+        board_pattern = re.compile(r"^ports/[^/]+/boards/([^/]+)/")
+        port_pattern = re.compile(r"^ports/([^/]+)/")
         for p in changed_files:
             # See if it is board specific
             board_matches = board_pattern.search(p)
@@ -120,7 +120,7 @@ def set_docs_to_build(build_all):
     doc_match = build_all
     if not build_all:
         doc_pattern = re.compile(
-            r"^(?:docs|extmod/ulab|(?:(?:ports\/\w+\/bindings|shared-bindings)\S+\.c|conf\.py|tools\/extract_pyi\.py|requirements-doc\.txt)$)|(?:-stubs|\.(?:md|MD|rst|RST))$"
+            r"^(?:docs|extmod/ulab|(?:(?:ports/\w+/bindings|shared-bindings)\S+\.c|conf\.py|tools/extract_pyi\.py|requirements-doc\.txt)$)|(?:-stubs|\.(?:md|MD|rst|RST))$"
         )
         for p in changed_files:
             if doc_pattern.search(p):