diff --git a/src/cfengine_cli/commands.py b/src/cfengine_cli/commands.py
index 6db55f2..aed5177 100644
--- a/src/cfengine_cli/commands.py
+++ b/src/cfengine_cli/commands.py
@@ -50,34 +50,33 @@ def deploy() -> int:
     return r
 
 
-def _format_filename(filename, line_length):
+def _format_filename(filename, line_length, check):
     if filename.startswith("./."):
-        return
+        return 0
     if filename.endswith(".json"):
-        format_json_file(filename)
-        return
+        return format_json_file(filename, check)
     if filename.endswith(".cf"):
-        format_policy_file(filename, line_length)
-        return
+        return format_policy_file(filename, line_length, check)
     raise UserError(f"Unrecognized file format: {filename}")
 
 
-def _format_dirname(directory, line_length):
+def _format_dirname(directory, line_length, check):
+    ret = 0
     for filename in find(directory, extension=".json"):
-        _format_filename(filename, line_length)
+        ret |= _format_filename(filename, line_length, check)
     for filename in find(directory, extension=".cf"):
-        _format_filename(filename, line_length)
+        ret |= _format_filename(filename, line_length, check)
+    return ret
 
 
-def format(names, line_length) -> int:
+def format(names, line_length, check) -> int:
     if not names:
-        _format_dirname(".", line_length)
-        return 0
+        return _format_dirname(".", line_length, check)
     if len(names) == 1 and names[0] == "-":
         # Special case, format policy file from stdin to stdout
-        format_policy_fin_fout(sys.stdin, sys.stdout, line_length)
-        return 0
+        return format_policy_fin_fout(sys.stdin, sys.stdout, line_length, check)
 
+    ret = 0
     for name in names:
         if name == "-":
             raise UserError(
@@ -86,12 +85,12 @@ def format(names, line_length) -> int:
         if not os.path.exists(name):
             raise UserError(f"{name} does not exist")
         if os.path.isfile(name):
-            _format_filename(name, line_length)
+            ret |= _format_filename(name, line_length, check)
             continue
         if os.path.isdir(name):
-            _format_dirname(name, line_length)
+            ret |= _format_dirname(name, line_length, check)
             continue
-    return 0
+    return ret
 
 
 def _lint(files, strict) -> int:
diff --git a/src/cfengine_cli/docs.py b/src/cfengine_cli/docs.py
index f0b7a80..6fa46b1 100644
--- a/src/cfengine_cli/docs.py
+++ b/src/cfengine_cli/docs.py
@@ -212,7 +212,7 @@ def fn_autoformat(_origin_path, snippet_path, language, _first_line, _last_line)
                 raise UserError(f"Invalid json in '{snippet_path}'")
         case "cf":
             # Note: Dead code - Not used for CFEngine policy yet
-            format_policy_file(snippet_path, 80)
+            format_policy_file(snippet_path, 80, False)
 
 
 def _translate_language(x):
diff --git a/src/cfengine_cli/format.py b/src/cfengine_cli/format.py
index da6063e..58615b9 100644
--- a/src/cfengine_cli/format.py
+++ b/src/cfengine_cli/format.py
@@ -1,13 +1,21 @@
 import tree_sitter_cfengine as tscfengine
 from tree_sitter import Language, Parser, Node
-from cfbs.pretty import pretty_file
+from cfbs.pretty import pretty_file, pretty_check_file
 
 
-def format_json_file(filename):
+def format_json_file(filename, check):
     assert filename.endswith(".json")
+
+    if check:
+        r = not pretty_check_file(filename)
+        if r:
+            print(f"JSON file '{filename}' needs reformatting")
+        return r
+
     r = pretty_file(filename)
     if r:
         print(f"JSON file '{filename}' was reformatted")
+    return r
 
 
 def text(node: Node):
@@ -534,8 +542,9 @@ def autoformat(node, fmt, line_length, macro_indent, indent=0):
     fmt.print(node, indent)
 
 
-def format_policy_file(filename, line_length):
+def format_policy_file(filename, line_length, check):
     assert filename.endswith(".cf")
+
     PY_LANGUAGE = Language(tscfengine.language())
     parser = Parser(PY_LANGUAGE)
 
@@ -551,12 +560,17 @@ def format_policy_file(filename, line_length):
 
     new_data = fmt.buffer + "\n"
     if new_data != original_data.decode("utf-8"):
+        if check:
+            print(f"Policy file '{filename}' needs reformatting")
+            return 1
+
         with open(filename, "w") as f:
             f.write(new_data)
         print(f"Policy file '{filename}' was reformatted")
+    return 0
 
 
-def format_policy_fin_fout(fin, fout, line_length):
+def format_policy_fin_fout(fin, fout, line_length, check):
     PY_LANGUAGE = Language(tscfengine.language())
     parser = Parser(PY_LANGUAGE)
 
@@ -571,3 +585,4 @@ def format_policy_fin_fout(fin, fout, line_length):
 
     new_data = fmt.buffer + "\n"
     fout.write(new_data)
+    return 0
diff --git a/src/cfengine_cli/main.py b/src/cfengine_cli/main.py
index adb96e3..68ac3cc 100644
--- a/src/cfengine_cli/main.py
+++ b/src/cfengine_cli/main.py
@@ -48,6 +48,7 @@ def _get_arg_parser():
     fmt = subp.add_parser("format", help="Autoformat .json and .cf files")
     fmt.add_argument("files", nargs="*", help="Files to format")
     fmt.add_argument("--line-length", default=80, type=int, help="Maximum line length")
+    fmt.add_argument("--check", action="store_true")
     lnt = subp.add_parser(
         "lint",
         help="Look for syntax errors and other simple mistakes",
@@ -136,7 +137,7 @@ def run_command_with_args(args) -> int:
     if args.command == "deploy":
         return commands.deploy()
     if args.command == "format":
-        return commands.format(args.files, args.line_length)
+        return commands.format(args.files, args.line_length, args.check)
     if args.command == "lint":
         return commands.lint(args.files, (args.strict.lower() in ("y", "ye", "yes")))
     if args.command == "report":