diff --git a/pdfminer/pdfdocument.py b/pdfminer/pdfdocument.py
index c170f1a..d638876 100644
--- a/pdfminer/pdfdocument.py
+++ b/pdfminer/pdfdocument.py
@@ -26,22 +26,21 @@ from utils import decode_text
 class PDFNoValidXRef(PDFSyntaxError):
     pass
 
-
 class PDFNoOutlines(PDFException):
     pass
 
-
 class PDFDestinationNotFound(PDFException):
     pass
 
-
 class PDFEncryptionError(PDFException):
     pass
 
-
 class PDFPasswordIncorrect(PDFEncryptionError):
     pass
 
+class PDFTextExtractionNotAllowed(PDFEncryptionError):
+    pass
+
 # some predefined literals and keywords.
 LITERAL_OBJSTM = LIT('ObjStm')
 LITERAL_XREF = LIT('XRef')
diff --git a/pdfminer/pdfinterp.py b/pdfminer/pdfinterp.py
index 2eda0ae..4b7a6b0 100644
--- a/pdfminer/pdfinterp.py
+++ b/pdfminer/pdfinterp.py
@@ -29,7 +29,6 @@ from utils import mult_matrix, MATRIX_IDENTITY
 class PDFResourceError(PDFException):
     pass
 
-
 class PDFInterpreterError(PDFException):
     pass
 
diff --git a/pdfminer/pdfpage.py b/pdfminer/pdfpage.py
index 95d12f3..154bbc3 100644
--- a/pdfminer/pdfpage.py
+++ b/pdfminer/pdfpage.py
@@ -7,15 +7,13 @@ from pdftypes import int_value, list_value, dict_value
 from pdfparser import PDFParser
 from pdfdocument import PDFDocument
 from pdfdocument import PDFEncryptionError
+from pdfdocument import PDFTextExtractionNotAllowed
 
 # some predefined literals and keywords.
 LITERAL_PAGE = LIT('Page')
 LITERAL_PAGES = LIT('Pages')
 
 
-class PDFTextExtractionNotAllowed(PDFEncryptionError):
-    pass
-
 ##  PDFPage
 ##
 class PDFPage(object):
diff --git a/pdfminer/pdftypes.py b/pdfminer/pdftypes.py
index 0c70bc9..0131382 100644
--- a/pdfminer/pdftypes.py
+++ b/pdfminer/pdftypes.py
@@ -25,23 +25,18 @@ LITERALS_DCT_DECODE = (LIT('DCTDecode'), LIT('DCT'))
 class PDFObject(PSObject):
     pass
 
-
 class PDFException(PSException):
     pass
 
-
 class PDFTypeError(PDFException):
     pass
 
-
 class PDFValueError(PDFException):
     pass
 
-
 class PDFObjectNotFound(PDFException):
     pass
 
-
 class PDFNotImplementedError(PDFException):
     pass