diff --git a/detection_rules/action_connector.py b/detection_rules/action_connector.py
index 404b92be4..7f98f58e2 100644
--- a/detection_rules/action_connector.py
+++ b/detection_rules/action_connector.py
@@ -105,7 +105,7 @@ class TOMLActionConnector:
         if path.suffix != ".toml":
             # If it doesn't, add one
             path = path.with_suffix(".toml")
-        with path.open("w") as f:
+        with path.open("w", encoding="utf-8") as f:
             contents_dict = self.contents.to_dict()
             # Sort the dictionary so that 'metadata' is at the top
             sorted_dict = dict(sorted(contents_dict.items(), key=lambda item: item[0] != "metadata"))
diff --git a/detection_rules/exception.py b/detection_rules/exception.py
index ead11ef5a..f67531a57 100644
--- a/detection_rules/exception.py
+++ b/detection_rules/exception.py
@@ -221,7 +221,7 @@ class TOMLException:
         if path.suffix != ".toml":
             # If it doesn't, add one
             path = path.with_suffix(".toml")
-        with path.open("w") as f:
+        with path.open("w", encoding="utf-8") as f:
             contents_dict = self.contents.to_dict()
             # Sort the dictionary so that 'metadata' is at the top
             sorted_dict = dict(sorted(contents_dict.items(), key=lambda item: item[0] != "metadata"))
diff --git a/detection_rules/rule_formatter.py b/detection_rules/rule_formatter.py
index 75225f160..16fe4733a 100644
--- a/detection_rules/rule_formatter.py
+++ b/detection_rules/rule_formatter.py
@@ -308,7 +308,7 @@ def toml_write(rule_contents: dict[str, Any], out_file_path: Path | None = None)
 
     f = None
     if out_file_path:
-        f = out_file_path.open("w")
+        f = out_file_path.open("w", encoding="utf-8")
 
     try:
         for data in ("metadata", "transform", "rule"):
diff --git a/detection_rules/rule_loader.py b/detection_rules/rule_loader.py
index 7fa84b32f..e2dfb936c 100644
--- a/detection_rules/rule_loader.py
+++ b/detection_rules/rule_loader.py
@@ -242,9 +242,9 @@ class RawRuleCollection(BaseCollection[DictRule]):
             # use pytoml instead of toml because of annoying bugs
             # https://github.com/uiri/toml/issues/152
             # might also be worth looking at https://github.com/sdispater/tomlkit
-            raw_dict = pytoml.loads(path.read_text())  # type: ignore[reportUnknownMemberType]
+            raw_dict = pytoml.loads(path.read_text(encoding="utf-8"))  # type: ignore[reportUnknownMemberType]
         elif path.suffix == ".json":
-            raw_dict = json.loads(path.read_text())
+            raw_dict = json.loads(path.read_text(encoding="utf-8"))
         elif path.suffix == ".ndjson":
             raise ValueError("ndjson is not supported in RawRuleCollection. Break out the rules individually.")
         else:
diff --git a/detection_rules/utils.py b/detection_rules/utils.py
index 1a67fed1e..eedd45d31 100644
--- a/detection_rules/utils.py
+++ b/detection_rules/utils.py
@@ -338,7 +338,7 @@ def rulename_to_filename(name: str, tactic_name: str | None = None, ext: str = "
 def load_rule_contents(rule_file: Path, single_only: bool = False) -> list[Any]:
     """Load a rule file from multiple formats."""
     extension = rule_file.suffix
-    raw_text = rule_file.read_text()
+    raw_text = rule_file.read_text(encoding="utf-8")
 
     if extension in (".ndjson", ".jsonl"):
         # kibana exported rule object is ndjson with the export metadata on the last line
diff --git a/pyproject.toml b/pyproject.toml
index 904d4eea5..362cb27c0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "detection_rules"
-version = "1.5.39"
+version = "1.5.40"
 description = "Detection Rules is the home for rules used by Elastic Security. This repository is used for the development, maintenance, testing, validation, and release of rules for Elastic Security’s Detection Engine."
 readme = "README.md"
 requires-python = ">=3.12"