diff --git a/beangrow/compute_returns.py b/beangrow/compute_returns.py
index bb4119d..9e5c1e5 100755
--- a/beangrow/compute_returns.py
+++ b/beangrow/compute_returns.py
@@ -73,7 +73,7 @@ def main():
     # Load, filter and expand the configuration.
     config = configlib.read_config(args.config, args.filter_reports, accounts)
     os.makedirs(args.output, exist_ok=True)
-    with open(path.join(args.output, "config.pbtxt"), "w") as efile:
+    with open(path.join(args.output, "config.pbtxt"), "w", encoding="utf8") as efile:
         print(config, file=efile)
 
     # Extract data from the ledger.
diff --git a/beangrow/compute_returns_beam.py b/beangrow/compute_returns_beam.py
index 83e69b4..d2541d7 100755
--- a/beangrow/compute_returns_beam.py
+++ b/beangrow/compute_returns_beam.py
@@ -84,7 +84,7 @@ def main():
     # Load, filter and expand the configuration.
     config = configlib.read_config(args.config, args.filter_reports, accounts)
     os.makedirs(args.output, exist_ok=True)
-    with open(path.join(args.output, "config.pbtxt"), "w") as efile:
+    with open(path.join(args.output, "config.pbtxt"), "w", encoding="utf8") as efile:
         print(config, file=efile)
 
     # Extract data from the ledger.
diff --git a/beangrow/config.py b/beangrow/config.py
index 30c5dd0..eaff5d6 100755
--- a/beangrow/config.py
+++ b/beangrow/config.py
@@ -83,7 +83,7 @@ def read_config(config_filename: str,
                 filter_reports: List[str],
                 accounts: List[Account]) -> Config:
     # Read the file.
-    with open(config_filename, "r") as infile:
+    with open(config_filename, "r", encoding="utf8") as infile:
         config_string = infile.read()
 
     return read_config_from_string(config_string, filter_reports, accounts)
diff --git a/beangrow/investments.py b/beangrow/investments.py
index 282247a..2d72186 100644
--- a/beangrow/investments.py
+++ b/beangrow/investments.py
@@ -486,7 +486,7 @@ def write_account_file(dcontext: display_context.DisplayContext,
     logging.info("Writing details file: %s", filename)
     epr = printer.EntryPrinter(dcontext=dcontext, stringify_invalid_types=True)
     os.makedirs(path.dirname(filename), exist_ok=True)
-    with open(filename, "w") as outfile:
+    with open(filename, "w", encoding="utf8") as outfile:
         fprint = partial(print, file=outfile)
         fprint(";; -*- mode: beancount; coding: utf-8; fill-column: 400 -*-")
 
@@ -553,7 +553,7 @@ def write_transactions_by_type(output_signatures: str,
         sigentries = data.sorted(sigentries)
 
         filename = "{}.org".format(sig)
-        with open(path.join(output_signatures, filename), "w") as catfile:
+        with open(path.join(output_signatures, filename), "w", encoding="utf8") as catfile:
             fprint = partial(print, file=catfile)
             fprint(";; -*- mode: beancount; coding: utf-8; fill-column: 400 -*-")
 
diff --git a/beangrow/reports.py b/beangrow/reports.py
index c33b8c6..261f25e 100755
--- a/beangrow/reports.py
+++ b/beangrow/reports.py
@@ -194,7 +194,7 @@ def write_returns_html(  # noqa: PLR0913
 
     logging.info("Writing returns dir for %s: %s", title, dirname)
     Path(dirname).mkdir(parents=True, exist_ok=True)
-    with Path(Path(dirname) / "index.html").open("w") as indexfile:
+    with Path(Path(dirname) / "index.html").open("w", encoding="utf8") as indexfile:
         fprint = partial(print, file=indexfile)
         fprint(RETURNS_TEMPLATE_PRE.format(style=STYLE, title=title))
 
@@ -338,7 +338,7 @@ def write_returns_debugfile(
     logging.info("Writing returns dir for %s: %s", title, filename)
     Path(filename).parent.mkdir(parents=True, exist_ok=True)
 
-    with Path(filename).open("w") as indexfile:
+    with Path(filename).open("w", encoding="utf8") as indexfile:
         fprint = partial(print, file=indexfile)
         fprint(f"* {title}")
         fprint("** Cash Flows")
@@ -540,7 +540,7 @@ def write_price_directives(
         price_entries.append(price)
 
     Path(filename).parent.mkdir(parents=True, exist_ok=True)
-    with Path(filename).open("w") as prfile:
+    with Path(filename).open("w", encoding="utf8") as prfile:
         printer.print_entries(price_entries, file=prfile)