diff --git a/.travis.yml b/.travis.yml
index d420e8c8..1bd4f370 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,7 @@ dist: trusty
 before_install:
   - sudo add-apt-repository ppa:heyarje/libav-11 -y
   - sudo add-apt-repository ppa:alex-p/tesseract-ocr -y
+  - sudo add-apt-repository ppa:evl.ms/evil -y # for a newer version (2.5.0) of pngquant
   - sudo apt-get update -qq
   - sudo apt-get install libleptonica-dev -y # required to build jbig2enc
   - sudo apt-get install zlib1g-dev -y       # required to build jbig2enc
@@ -14,6 +15,8 @@ before_install:
 script:
   - export OCRMYPDF_VERSION=8.3.2
   - bash build-appimage.sh
+  - # remove previous installed libraries to ensure that the tests use the libraries of the AppImage
+  - sudo apt-get remove libleptonica-dev zlib1g-dev -y
   - bash test/test-appimage.sh
   - wget https://github.com/probonopd/uploadtool/raw/master/upload.sh
 
diff --git a/test/test-appimage.sh b/test/test-appimage.sh
index 17d7a92d..002e5264 100644
--- a/test/test-appimage.sh
+++ b/test/test-appimage.sh
@@ -39,22 +39,7 @@ run_appimage
 
 run_appimagelint
 
-# run_pytest # commented out in order to get the AppImage uploaded to github release
+ run_pytest
 
-# 'test_flate_to_jbig2' fails
-# >       assert pim.filters[0] == '/JBIG2Decode'
-# E       AssertionError: assert '/FlateDecode' == '/JBIG2Decode'
-# E         - /FlateDecode
-# E         + /JBIG2Decode
-
-# ../OCRmyPDF/tests/test_optimize.py:131: AssertionError
-# ----------------------------- Captured stderr call -----------------------------
-#    INFO - Input file is not a PDF, checking if it is an image...
-#    INFO - Input file is an image
-#    INFO - Image seems valid. Try converting to PDF...
-#    INFO - Successfully converted to PDF, processing...
-# pngquant: unrecognized option '--skip-if-larger'
-#    INFO - Optimize ratio: 1.02 savings: 1.7%
-#    INFO - Output file is a PDF/A-2B (as expected)