diff --git a/requirements.txt b/requirements.txt
index 76566e6..e66d39b 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -12,7 +12,7 @@ chardet==3.0.4
 click==6.7
 cogent==1.5.3
 conda==4.3.30
-cryptography==2.0.3
+cryptography==2.3
 cutadapt==1.14
 cycler==0.10.0
 decorator==4.1.2