diff --git a/pydocx/openxml/wordprocessing/simple_field.py b/pydocx/openxml/wordprocessing/simple_field.py
index 116d4b0c..f34fe8e3 100644
--- a/pydocx/openxml/wordprocessing/simple_field.py
+++ b/pydocx/openxml/wordprocessing/simple_field.py
@@ -38,6 +38,8 @@ def _parse_instr_arg_string_to_args(self, arg_string):
         return re.findall(r'\s*(?:"([^"]+)"|([^\s]+))+', arg_string)
 
     def parse_instr(self):
+        if self.instr is None:
+            return
         m = self._parse_instr_into_field_type_and_arg_string()
         if not m:
             return
diff --git a/tests/export/html/test_simple_field.py b/tests/export/html/test_simple_field.py
index c16aa8b5..75170097 100644
--- a/tests/export/html/test_simple_field.py
+++ b/tests/export/html/test_simple_field.py
@@ -202,6 +202,10 @@ def parse(self, instr):
         field = SimpleField(instr=instr)
         return field.parse_instr()
 
+    def test_with_None_instr_returns_None(self):
+        result = self.parse(None)
+        self.assertEqual(result, None)
+
     def test_with_blank_instr_returns_None(self):
         result = self.parse('')
         self.assertEqual(result, None)