diff --git a/msgpack/__init__.py b/msgpack/__init__.py
index 7493c4c..2143ecb 100644
--- a/msgpack/__init__.py
+++ b/msgpack/__init__.py
@@ -1,6 +1,21 @@
 # coding: utf-8
 from msgpack._version import version
-from msgpack.exceptions import *
+from msgpack.exceptions import (
+    UnpackException,
+    BufferFull,
+    OutOfData,
+    UnpackValueError,
+    ExtraData,
+    PackException,
+    PackValueError,
+    PackOverflowError,
+    InvalidSequence,
+    NestLimitExceeded,
+)
+
+# Aliases for backward compatibility / test expectations
+FormatError = InvalidSequence
+StackError = NestLimitExceeded
 
 from collections import namedtuple
 
diff --git a/msgpack/exceptions.py b/msgpack/exceptions.py
index 5bee5b2..fe371c8 100644
--- a/msgpack/exceptions.py
+++ b/msgpack/exceptions.py
@@ -36,3 +36,18 @@ class ExtraData(UnpackValueError):
 PackException = Exception
 PackValueError = ValueError
 PackOverflowError = OverflowError
+
+
+class InvalidSequence(ValueError):
+    """The data is not a valid msgpack sequence."""
+    pass
+
+
+class NestLimitExceeded(ValueError):
+    """The nesting limit has been exceeded."""
+    pass
+
+
+# Aliases for external compatibility
+FormatError = InvalidSequence
+StackError = NestLimitExceeded
diff --git a/msgpack/fallback.py b/msgpack/fallback.py
index 04fb5b9..b4ffc7e 100644
--- a/msgpack/fallback.py
+++ b/msgpack/fallback.py
@@ -52,7 +52,9 @@ else:
 from msgpack.exceptions import (
     BufferFull,
     OutOfData,
-    ExtraData)
+    ExtraData,
+    FormatError,
+    StackError)
 
 from msgpack import ExtType
 
@@ -561,11 +563,13 @@ class Unpacker(object):
                 raise ValueError("%s exceeds max_map_len(%s)", n, self._max_map_len)
             typ = TYPE_MAP
         else:
-            raise ValueError("Unknown header: 0x%x" % b)
+            raise FormatError("Unknown header: 0x%x" % b)
         return typ, n, obj
 
-    def _unpack(self, execute=EX_CONSTRUCT):
+    def _unpack(self, execute=EX_CONSTRUCT, _depth=0):
         typ, n, obj = self._read_header(execute)
+        if _depth >= DEFAULT_RECURSE_LIMIT:
+            raise StackError("Nested too deep")
 
         if execute == EX_READ_ARRAY_HEADER:
             if typ != TYPE_ARRAY:
@@ -584,7 +588,7 @@ class Unpacker(object):
                 return
             ret = newlist_hint(n)
             for i in xrange(n):
-                ret.append(self._unpack(EX_CONSTRUCT))
+                ret.append(self._unpack(EX_CONSTRUCT, _depth+1))
             if self._list_hook is not None:
                 ret = self._list_hook(ret)
             # TODO is the interaction between `list_hook` and `use_list` ok?
@@ -598,14 +602,14 @@ class Unpacker(object):
                 return
             if self._object_pairs_hook is not None:
                 ret = self._object_pairs_hook(
-                    (self._unpack(EX_CONSTRUCT),
-                     self._unpack(EX_CONSTRUCT))
+                    (self._unpack(EX_CONSTRUCT, _depth+1),
+                     self._unpack(EX_CONSTRUCT, _depth+1))
                     for _ in xrange(n))
             else:
                 ret = {}
                 for _ in xrange(n):
-                    key = self._unpack(EX_CONSTRUCT)
-                    ret[key] = self._unpack(EX_CONSTRUCT)
+                    key = self._unpack(EX_CONSTRUCT, _depth+1)
+                    ret[key] = self._unpack(EX_CONSTRUCT, _depth+1)
                 if self._object_hook is not None:
                     ret = self._object_hook(ret)
             return ret