diff --git a/partd/compatibility.py b/partd/compatibility.py
index 20a217a..c74cd91 100644
--- a/partd/compatibility.py
+++ b/partd/compatibility.py
@@ -12,3 +12,4 @@
     unicode = unicode
     import cPickle as pickle
     from Queue import Queue, Empty
+
diff --git a/partd/pandas.py b/partd/pandas.py
index db3a208..6a6da92 100644
--- a/partd/pandas.py
+++ b/partd/pandas.py
@@ -12,7 +12,6 @@
 from .encode import Encode
 from .utils import extend, framesplit, frame
 
-
 try:
     # pandas >= 0.24.0
     from pandas.api.types import is_extension_array_dtype
@@ -20,6 +19,18 @@
     def is_extension_array_dtype(dtype):
         return False
 
+try:
+    # Some `ExtensionArray`s can have a `.dtype` which is not a `ExtensionDtype`
+    # (e.g. they can be backed by a NumPy dtype). For these cases we check
+    # whether the instance is a `ExtensionArray`.
+    # https://github.com/dask/partd/issues/48
+    from pandas.api.extensions import ExtensionArray
+    def is_extension_array(x):
+        return isinstance(x, ExtensionArray)
+except ImportError:
+    def is_extension_array(x):
+        return False
+
 
 dumps = partial(pickle.dumps, protocol=pickle.HIGHEST_PROTOCOL)
 
@@ -129,7 +140,7 @@ def block_to_header_bytes(block):
     elif is_datetime64tz_dtype(block):
         extension = ('datetime64_tz_type', (block.values.tzinfo,))
         values = values.view('i8')
-    elif is_extension_array_dtype(block.dtype):
+    elif is_extension_array_dtype(block.dtype) or is_extension_array(values):
         extension = ("other", ())
     else:
         extension = ('numpy_type', ())