diff --git a/requirements.txt b/requirements.txt
index db768e8..db8fc3f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -13,7 +13,7 @@ cffi==1.11.5              # via cryptography
 chardet==3.0.4            # via requests
 click==6.7                # via mootdx, pytdx
 coloredlogs==10.0
-cryptography==2.3.1       # via pytdx
+cryptography==2.8       # via pytdx
 cycler==0.10.0            # via matplotlib
 cython==0.28.5
 humanfriendly==4.16.1     # via coloredlogs
diff --git a/tests/requirements.txt b/tests/requirements.txt
index 446044f..6c932d0 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -1,7 +1,7 @@
 flake8==3.5.0
 tox==3.4.0
 coverage==4.5.1
-cryptography==2.3.1
+cryptography==2.8
 PyYAML==3.13
 pytest==3.8.1
 pytest-runner==4.2