diff --git a/bookwyrm/models/book.py b/bookwyrm/models/book.py
index e32846fea..d6b48b57e 100644
--- a/bookwyrm/models/book.py
+++ b/bookwyrm/models/book.py
@@ -1,4 +1,6 @@
 ''' database schema for books and shelves '''
+import re
+
 from django.db import models
 from django.utils import timezone
 from django.utils.http import http_date
@@ -186,14 +188,18 @@ class Edition(Book):
 
 def isbn_10_to_13(isbn_10):
     ''' convert an isbn 10 into an isbn 13 '''
+    isbn_10 = re.sub(r'[^0-9X]', '', isbn_10)
     # drop the last character of the isbn 10 number (the original checkdigit)
     converted = isbn_10[:9]
     # add "978" to the front
     converted = '978' + converted
     # add a check digit to the end
     # multiply the odd digits by 1 and the even digits by 3 and sum them
-    checksum = sum(int(i) for i in converted[::2]) + \
+    try:
+        checksum = sum(int(i) for i in converted[::2]) + \
                sum(int(i) * 3 for i in converted[1::2])
+    except ValueError:
+        return None
     # add the checksum mod 10 to the end
     checkdigit = checksum % 10
     if checkdigit != 0:
@@ -206,11 +212,16 @@ def isbn_13_to_10(isbn_13):
     if isbn_13[:3] != '978':
         return None
 
+    isbn_13 = re.sub(r'[^0-9X]', '', isbn_13)
+
     # remove '978' and old checkdigit
     converted = isbn_13[3:-1]
     # calculate checkdigit
     # multiple each digit by 10,9,8.. successively and sum them
-    checksum = sum(int(d) * (10 - idx)  for (idx, d) in enumerate(converted))
+    try:
+        checksum = sum(int(d) * (10 - idx) for (idx, d) in enumerate(converted))
+    except ValueError:
+        return None
     checkdigit = checksum % 11
     checkdigit = 11 - checkdigit
     if checkdigit == 10:
diff --git a/bookwyrm/tests/models/test_book_model.py b/bookwyrm/tests/models/test_book_model.py
index 78567a92f..e8211a8f9 100644
--- a/bookwyrm/tests/models/test_book_model.py
+++ b/bookwyrm/tests/models/test_book_model.py
@@ -54,11 +54,21 @@ class Book(TestCase):
         isbn_13 = isbn_10_to_13(isbn_10)
         self.assertEqual(isbn_13, '9781788161671')
 
+        isbn_10 = '1-788-16167-X'
+        isbn_13 = isbn_10_to_13(isbn_10)
+        self.assertEqual(isbn_13, '9781788161671')
+
+
+
     def test_isbn_13_to_10(self):
         isbn_13 = '9781788161671'
         isbn_10 = isbn_13_to_10(isbn_13)
         self.assertEqual(isbn_10, '178816167X')
 
+        isbn_13 = '978-1788-16167-1'
+        isbn_10 = isbn_13_to_10(isbn_13)
+        self.assertEqual(isbn_10, '178816167X')
+
 
 class Shelf(TestCase):
     def setUp(self):