diff --git a/awscli/customizations/configure/writer.py b/awscli/customizations/configure/writer.py
index 83825a53dab6..78fe84d15eea 100644
--- a/awscli/customizations/configure/writer.py
+++ b/awscli/customizations/configure/writer.py
@@ -215,30 +215,36 @@ def _update_section_contents(self, contents, section_name, new_values):
 
     def _update_subattributes(self, index, contents, values, starting_indent):
         index += 1
+        last_subattribute_line = index - 1
         for i in range(index, len(contents)):
             line = contents[i]
+            if self.SECTION_REGEX.search(line) is not None:
+                self._insert_new_values(i - 1, contents, values, '    ')
+                return i
             match = self.OPTION_REGEX.search(line)
-            if match is not None:
-                current_indent = len(
-                    match.group(1)) - len(match.group(1).lstrip())
-                key_name = match.group(1).strip()
-                if key_name in values:
-                    option_value = values[key_name]
-                    new_line = '%s%s = %s\n' % (' ' * current_indent,
-                                                key_name, option_value)
-                    contents[i] = new_line
-                    del values[key_name]
-            if starting_indent == current_indent or \
-                    self.SECTION_REGEX.search(line) is not None:
+            if match is None:
+                last_subattribute_line = i
+                continue
+            current_indent = len(
+                match.group(1)) - len(match.group(1).lstrip())
+            if starting_indent == current_indent:
                 # We've arrived at the starting indent level so we can just
                 # write out all the values now.
                 self._insert_new_values(i - 1, contents, values, '    ')
-                break
-        else:
-            if starting_indent != current_indent:
-                # The option is the last option in the file
-                self._insert_new_values(i, contents, values, '    ')
-        return i
+                return i
+            key_name = match.group(1).strip()
+            if key_name in values:
+                option_value = values[key_name]
+                new_line = '%s%s = %s\n' % (
+                    ' ' * current_indent,
+                    key_name,
+                    option_value,
+                )
+                contents[i] = new_line
+                del values[key_name]
+            last_subattribute_line = i
+        self._insert_new_values(last_subattribute_line, contents, values, '    ')
+        return last_subattribute_line
 
     def _insert_new_values(self, line_number, contents, new_values, indent=''):
         new_contents = []
diff --git a/tests/unit/customizations/configure/test_writer.py b/tests/unit/customizations/configure/test_writer.py
index 9c85516762ef..7ce63f7d6e58 100644
--- a/tests/unit/customizations/configure/test_writer.py
+++ b/tests/unit/customizations/configure/test_writer.py
@@ -295,6 +295,34 @@ def test_add_to_nested_with_nested_in_the_end(self):
             '    other = foo\n'
             '    signature_version = newval\n')
 
+    def test_add_to_empty_nested_block_at_end_of_file(self):
+        original = (
+            '[default]\n'
+            's3 =\n'
+        )
+        self.assert_update_config(
+            original, {'__section__': 'default',
+                       's3': {'signature_version': 'newval'}},
+            '[default]\n'
+            's3 =\n'
+            '    signature_version = newval\n')
+
+    def test_add_to_nested_with_comment_in_block(self):
+        original = (
+            '[default]\n'
+            's3 =\n'
+            '# comment\n'
+            '    addressing_style = path\n'
+        )
+        self.assert_update_config(
+            original, {'__section__': 'default',
+                       's3': {'signature_version': 'newval'}},
+            '[default]\n'
+            's3 =\n'
+            '# comment\n'
+            '    addressing_style = path\n'
+            '    signature_version = newval\n')
+
     def test_update_nested_attribute(self):
         original = (
             '[default]\n'
@@ -326,6 +354,22 @@ def test_updated_nested_attribute_new_section(self):
             '[profile foo]\n'
             'foo = bar\n')
 
+    def test_add_to_nested_with_next_section_header(self):
+        original = (
+            '[default]\n'
+            's3 =\n'
+            '[profile foo]\n'
+            'foo = bar\n'
+        )
+        self.assert_update_config(
+            original, {'__section__': 'default',
+                       's3': {'signature_version': 'newval'}},
+            '[default]\n'
+            's3 =\n'
+            '    signature_version = newval\n'
+            '[profile foo]\n'
+            'foo = bar\n')
+
     def test_update_nested_attr_no_prior_nesting(self):
         original = (
             '[default]\n'
@@ -343,6 +387,20 @@ def test_update_nested_attr_no_prior_nesting(self):
             '[profile foo]\n'
             'foo = bar\n')
 
+    def test_nested_attribute_does_not_update_same_indent_sibling(self):
+        original = (
+            '[default]\n'
+            's3 =\n'
+            'region = oldval\n'
+        )
+        self.assert_update_config(
+            original, {'__section__': 'default',
+                       's3': {'region': 'newval'}},
+            '[default]\n'
+            's3 =\n'
+            '    region = newval\n'
+            'region = oldval\n')
+
     def test_can_handle_empty_section(self):
         original = (
             '[default]\n'