diff --git a/pyporter/utils.py b/pyporter/utils.py
index 1c8e3d4a833836b30f49f8ac7ab0671160cd7f93..932e2974b19636da23512049097b5b3b06a482fb 100644
--- a/pyporter/utils.py
+++ b/pyporter/utils.py
@@ -3,17 +3,22 @@ import re
 
 # TODO: this should be more compatible for https://peps.python.org/pep-0508/
 def transform_module_name(input_str):
-    module_name = re.match(r"([a-zA-Z0-9_-]+)", input_str).group(1).strip()
-    version_names = input_str[len(module_name):].strip().strip("()")
-    version_constraint = version_names.split(",")
-    package_name = "python3-" + module_name
-    if len(version_constraint) > 1:
-        constraints_string = " with ".join([
-            f"{package_name}{constraint}" for constraint in version_constraint
-        ])
-        result_string = f"({constraints_string})"
+    match = re.match(r"([a-zA-Z0-9_-]+)", input_str)
+    if match:
+        module_name = match.group(1).strip()
+
+        version_names = input_str[len(module_name):].strip().strip("()")
+        version_constraint = version_names.split(",")
+        package_name = "python3-" + module_name
+        if len(version_constraint) > 1:
+            constraints_string = " with ".join([
+                f"{package_name}{constraint}" for constraint in version_constraint
+            ])
+            result_string = f"({constraints_string})"
+        else:
+            result_string = f"({package_name}{version_constraint[0]})"
     else:
-        result_string = f"({package_name}{version_constraint[0]})"
+        result_string = "Invalid input format"
 
     return result_string
 
diff --git a/tests/test_transform_module_name.py b/tests/test_transform_module_name.py
index c292b7d90fadf27593d879e9b4ef4a172ba3a33a..de53d7bb0a499e883420b874c9906757de7d08c0 100644
--- a/tests/test_transform_module_name.py
+++ b/tests/test_transform_module_name.py
@@ -16,9 +16,14 @@ class TestTransofrmModuleName(unittest.TestCase):
 
     def test_transform_module_name_strip_whitespace(self):
         input_str = "pyjwkest (>=1.3.6)"
-        expected_output = "(python3-pyjwkest(>=1.3.6))"
+        expected_output = "(python3-pyjwkest>=1.3.6)"
         self.assertEqual(transform_module_name(input_str), expected_output)
 
+    def test_invalid_input(self):
+        input_str = "!invalid_module123"
+        expected_output = "Invalid input format"
+        self.assertEqual(transform_module_name(input_str), expected_output)    
+
 
 if __name__ == '__main__':
     unittest.main()