diff --git a/tests/fields/fields.py b/tests/fields/fields.py
index 7c4e7853..124c9538 100644
--- a/tests/fields/fields.py
+++ b/tests/fields/fields.py
@@ -1950,7 +1950,7 @@ class FieldTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
@@ -1973,7 +1973,7 @@ class FieldTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
@@ -1996,7 +1996,7 @@ class FieldTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
@@ -2019,7 +2019,7 @@ class FieldTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
diff --git a/tests/fields/file_tests.py b/tests/fields/file_tests.py
index a39dadbf..44d28626 100644
--- a/tests/fields/file_tests.py
+++ b/tests/fields/file_tests.py
@@ -208,7 +208,7 @@ class FileTest(unittest.TestCase):
         Animal.drop_collection()
         marmot = Animal(genus='Marmota', family='Sciuridae')
 
-        marmot_photo = open(TEST_IMAGE_PATH, 'r')  # Retrieve a photo from disk
+        marmot_photo = open(TEST_IMAGE_PATH, 'rb')  # Retrieve a photo from disk
         marmot.photo.put(marmot_photo, content_type='image/jpeg', foo='bar')
         marmot.photo.close()
         marmot.save()
@@ -251,7 +251,7 @@ class FileTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
@@ -274,7 +274,7 @@ class FileTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
@@ -297,7 +297,7 @@ class FileTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()
@@ -320,7 +320,7 @@ class FileTest(unittest.TestCase):
         TestImage.drop_collection()
 
         t = TestImage()
-        t.image.put(open(TEST_IMAGE_PATH, 'r'))
+        t.image.put(open(TEST_IMAGE_PATH, 'rb'))
         t.save()
 
         t = TestImage.objects.first()