diff --git a/sops/__init__.py b/sops/__init__.py
index c358e13a9..5b3e82e28 100644
--- a/sops/__init__.py
+++ b/sops/__init__.py
@@ -36,6 +36,13 @@ else:
     import json
     from collections import OrderedDict
 
+try:
+    from collections.abc import MutableMapping
+    from collections.abc import MutableSequence
+except ImportError:
+    from collections import MutableMapping
+    from collections import MutableSequence
+
 if sys.version_info[0] == 3:
     raw_input = input
 
@@ -564,7 +571,10 @@ def verify_or_create_sops_branch(tree, kms_arns=None, pgp_fps=None,
         tree['sops']['version'] = VERSION
         tree['sops']['unencrypted_suffix'] = UNENCRYPTED_SUFFIX
 
-    if 'kms' in tree['sops'] and isinstance(tree['sops']['kms'], list):
+    if (
+        'kms' in tree['sops']
+        and isinstance(tree['sops']['kms'], MutableSequence)
+    ):
         # check that we have at least one ARN to work with
         for entry in tree['sops']['kms']:
             if (entry and 'arn' in entry and entry['arn'] != "" and
@@ -572,7 +582,10 @@ def verify_or_create_sops_branch(tree, kms_arns=None, pgp_fps=None,
                 return tree, need_new_data_key
 
     # if we're here, no data key was found in the kms entries
-    if 'pgp' in tree['sops'] and isinstance(tree['sops']['pgp'], list):
+    if (
+        'pgp' in tree['sops']
+        and isinstance(tree['sops']['pgp'], MutableSequence)
+    ):
         # check that we have at least one fingerprint to work with
         for entry in tree['sops']['pgp']:
             if (entry and 'fp' in entry and entry['fp'] != "" and
@@ -653,7 +666,7 @@ def update_master_keys(tree, key):
         with them, and store the new encrypted values.
     """
     if 'kms' in tree['sops']:
-        if not isinstance(tree['sops']['kms'], list):
+        if not isinstance(tree['sops']['kms'], MutableSequence):
             panic("invalid KMS format in SOPS branch, must be a list")
         i = -1
         for entry in tree['sops']['kms']:
@@ -667,7 +680,7 @@ def update_master_keys(tree, key):
                 tree['sops']['kms'][i] = updated
 
     if 'pgp' in tree['sops']:
-        if not isinstance(tree['sops']['pgp'], list):
+        if not isinstance(tree['sops']['pgp'], MutableSequence):
             panic("invalid PGP format in SOPS branch, must be a list")
         i = -1
         for entry in tree['sops']['pgp']:
@@ -815,11 +828,11 @@ def walk_and_decrypt(branch, key, aad=b'', stash=None, digest=None,
         if stash:
             stash[k] = {'has_stash': True}
             nstash = stash[k]
-        if isinstance(v, dict):
+        if isinstance(v, MutableMapping):
             branch[k] = walk_and_decrypt(v, key, aad=caad, stash=nstash,
                                          digest=digest, isRoot=False,
                                          unencrypted=unencrypted_branch)
-        elif isinstance(v, list):
+        elif isinstance(v, MutableSequence):
             branch[k] = walk_list_and_decrypt(v, key, aad=caad, stash=nstash,
                                               digest=digest,
                                               unencrypted=unencrypted_branch)
@@ -857,11 +870,11 @@ def walk_list_and_decrypt(branch, key, aad=b'', stash=None, digest=None,
         if stash:
             stash[i] = {'has_stash': True}
             nstash = stash[i]
-        if isinstance(v, dict):
+        if isinstance(v, MutableMapping):
             kl.append(walk_and_decrypt(v, key, aad=aad, stash=nstash,
                                        digest=digest, isRoot=False,
                                        unencrypted=unencrypted))
-        elif isinstance(v, list):
+        elif isinstance(v, MutableSequence):
             kl.append(walk_list_and_decrypt(v, key, aad=aad, stash=nstash,
                                             digest=digest,
                                             unencrypted=unencrypted))
@@ -950,12 +963,12 @@ def walk_and_encrypt(branch, key, aad=b'', stash=None,
         nstash = dict()
         if stash and k in stash:
             nstash = stash[k]
-        if isinstance(v, dict):
+        if isinstance(v, MutableMapping):
             # recursively walk the tree
             branch[k] = walk_and_encrypt(v, key, aad=caad, stash=nstash,
                                          digest=digest, isRoot=False,
                                          unencrypted=unencrypted_branch)
-        elif isinstance(v, list):
+        elif isinstance(v, MutableSequence):
             branch[k] = walk_list_and_encrypt(v, key, aad=caad, stash=nstash,
                                               digest=digest,
                                               unencrypted=unencrypted_branch)
@@ -985,11 +998,11 @@ def walk_list_and_encrypt(branch, key, aad=b'', stash=None, digest=None,
     for i, v in enumerate(list(branch)):
         if stash and i in stash:
             nstash = stash[i]
-        if isinstance(v, dict):
+        if isinstance(v, MutableMapping):
             kl.append(walk_and_encrypt(v, key, aad=aad, stash=nstash,
                                        digest=digest, isRoot=False,
                                        unencrypted=unencrypted))
-        elif isinstance(v, list):
+        elif isinstance(v, MutableSequence):
             kl.append(walk_list_and_encrypt(v, key, aad=aad, stash=nstash,
                                             digest=digest,
                                             unencrypted=unencrypted))
@@ -1134,6 +1147,14 @@ def get_key_from_kms(tree):
                           entry['arn'])
             continue
         context = entry['context'] if 'context' in entry else {}
+        if (
+            not isinstance(context, dict)
+            and isinstance(context, MutableMapping)
+        ):
+            # ruamel.yaml's CommentedMap no longer subclasses dict as of
+            # 0.15.52, but botocore only accepts dict subclasses, so unpack the
+            # context as an unordered, uncommented dict.
+            context = dict(**context)
         try:
             kms_response = kms.decrypt(CiphertextBlob=b64decode(enc),
                                        EncryptionContext=context)
@@ -1292,7 +1313,10 @@ def write_file(tree, path=None, filetype=None):
         fd = tempfile.NamedTemporaryFile(suffix="."+filetype, delete=False)
         path = fd.name
 
-    if not isinstance(tree, dict) and not isinstance(tree, list):
+    if (
+        not isinstance(tree, MutableMapping)
+        and not isinstance(tree, MutableSequence)
+    ):
         if path == 'stdout':
             sys.stdout.write(tree.encode('utf-8'))
         else: