diff --git a/app/environment.yml b/app/environment.yml
index b60228da..5b093b93 100644
--- a/app/environment.yml
+++ b/app/environment.yml
@@ -49,7 +49,7 @@ dependencies:
 - werkzeug=0.11.15=py27_0
 - wheel=0.29.0=py27_0
 - xz=5.2.2=1
-- zlib=1.2.8=3
+- zlib
 - keepalive=0.5=py27_0
 - mmtf-python=1.0.5=py27_0
 - rdflib=4.2.1=py27_0