diff --git a/Tests/test_file_pdf.py b/Tests/test_file_pdf.py
index 4bc70d10c..ed6b50b5d 100644
--- a/Tests/test_file_pdf.py
+++ b/Tests/test_file_pdf.py
@@ -15,6 +15,14 @@ def helper_save_as_pdf(mode):
     assert_greater(os.path.getsize(outfile), 0)
 
 
+def test_monochrome():
+    # Arrange
+    mode = "1"
+
+    # Act / Assert
+    helper_save_as_pdf(mode)
+
+
 def test_greyscale():
     # Arrange
     mode = "L"
@@ -33,9 +41,11 @@ def test_rgb():
 
 # FIXME: P-mode test fails on Python 3.
 # https://travis-ci.org/hugovk/Pillow/builds/24915249
-#   File "/home/travis/build/hugovk/Pillow/PIL/PdfImagePlugin.py", line 108, in _save
+#   File "/home/travis/build/hugovk/Pillow/PIL/PdfImagePlugin.py", line 108,
+#   in _save
 #     colorspace = colorspace + b"> ]"
 # TypeError: Can't convert 'bytes' object to str implicitly
+
 # def test_p_mode():
 #     # Arrange
 #     mode = "P"