diff --git a/Tools/cases_generator/lexer.py b/Tools/cases_generator/lexer.py
index 79bb9c27a55601..1ab636dc5ea778 100644
--- a/Tools/cases_generator/lexer.py
+++ b/Tools/cases_generator/lexer.py
@@ -389,7 +389,8 @@ def to_text(tkns: list[Token], dedent: int = 0) -> str:
     if filename == "-c":
         src = sys.argv[2]
     else:
-        src = open(filename).read()
+        with open(filename, encoding="utf-8") as f:
+            src = f.read()
     # print(to_text(tokenize(src)))
     for tkn in tokenize(src, filename=filename):
         print(tkn)
diff --git a/Tools/cases_generator/parser.py b/Tools/cases_generator/parser.py
index ccf8bf649520ff..cd21d10c5a63ab 100644
--- a/Tools/cases_generator/parser.py
+++ b/Tools/cases_generator/parser.py
@@ -42,7 +42,7 @@ def prettify_filename(filename: str) -> str:
 def parse_files(filenames: list[str]) -> list[AstNode]:
     result: list[AstNode] = []
     for filename in filenames:
-        with open(filename) as file:
+        with open(filename, encoding="utf-8") as file:
             src = file.read()
 
         psr = Parser(src, filename=prettify_filename(filename))
diff --git a/Tools/cases_generator/plexer.py b/Tools/cases_generator/plexer.py
index 95a68cf1562111..92a806295426ee 100644
--- a/Tools/cases_generator/plexer.py
+++ b/Tools/cases_generator/plexer.py
@@ -110,7 +110,7 @@ def make_syntax_error(self, message: str, tkn: Token | None = None) -> SyntaxErr
             src = sys.argv[2]
             filename = "<string>"
         else:
-            with open(filename) as f:
+            with open(filename, encoding="utf-8") as f:
                 src = f.read()
     else:
         filename = "<default>"