diff --git a/python/pyspark/sql/types.py b/python/pyspark/sql/types.py
index 1f6534836d64..3cd7a2ef115a 100644
--- a/python/pyspark/sql/types.py
+++ b/python/pyspark/sql/types.py
@@ -289,7 +289,8 @@ def __init__(self, elementType, containsNull=True):
         >>> ArrayType(StringType(), False) == ArrayType(StringType())
         False
         """
-        assert isinstance(elementType, DataType), "elementType should be DataType"
+        assert isinstance(elementType, DataType),\
+            "elementType %s should be an instance of %s" % (elementType, DataType)
         self.elementType = elementType
         self.containsNull = containsNull
 
@@ -343,8 +344,10 @@ def __init__(self, keyType, valueType, valueContainsNull=True):
         ...        == MapType(StringType(), FloatType()))
         False
         """
-        assert isinstance(keyType, DataType), "keyType should be DataType"
-        assert isinstance(valueType, DataType), "valueType should be DataType"
+        assert isinstance(keyType, DataType),\
+            "keyType %s should be an instance of %s" % (keyType, DataType)
+        assert isinstance(valueType, DataType),\
+            "valueType %s should be an instance of %s" % (valueType, DataType)
         self.keyType = keyType
         self.valueType = valueType
         self.valueContainsNull = valueContainsNull
@@ -402,8 +405,9 @@ def __init__(self, name, dataType, nullable=True, metadata=None):
         ...      == StructField("f2", StringType(), True))
         False
         """
-        assert isinstance(dataType, DataType), "dataType should be DataType"
-        assert isinstance(name, basestring), "field name should be string"
+        assert isinstance(dataType, DataType),\
+            "dataType %s should be an instance of %s" % (dataType, DataType)
+        assert isinstance(name, basestring), "field name %s should be string" % (name)
         if not isinstance(name, str):
             name = name.encode('utf-8')
         self.name = name