diff --git a/PyPDF2/pdf.py b/PyPDF2/pdf.py
index 9fff2a8..c5cae9e 100644
--- a/PyPDF2/pdf.py
+++ b/PyPDF2/pdf.py
@@ -1667,11 +1667,12 @@ class PdfFileReader(object):
                     raise utils.PdfReadError("Expected object ID (%d %d) does not match actual (%d %d); xref table not zero-indexed." \
                                      % (indirectReference.idnum, indirectReference.generation, idnum, generation))
                 else: pass # xref table is corrected in non-strict mode
-            elif idnum != indirectReference.idnum:
+            elif idnum != indirectReference.idnum and self.strict:
                 # some other problem
                 raise utils.PdfReadError("Expected object ID (%d %d) does not match actual (%d %d)." \
                                          % (indirectReference.idnum, indirectReference.generation, idnum, generation))
-            assert generation == indirectReference.generation
+            if self.strict:
+                assert generation == indirectReference.generation
             retval = readObject(self.stream, self)
 
             # override encryption is used for the /Encrypt dictionary