diff --git a/README.md b/README.md
index 3afb4920..10e67938 100644
--- a/README.md
+++ b/README.md
@@ -49,6 +49,7 @@ out = ecg.ecg(signal=signal, sampling_rate=1000., show=True)
 - scikit-learn
 - scipy
 - shortuuid
+- six
 
 ## License
 
diff --git a/README.rst b/README.rst
index f235c3e8..a26a056c 100644
--- a/README.rst
+++ b/README.rst
@@ -54,6 +54,7 @@ Dependencies
 -  scikit-learn
 -  scipy
 -  shortuuid
+-  six
 
 License
 -------
diff --git a/requirements.txt b/requirements.txt
index e699e9d4..e5c154b3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,8 +1,8 @@
 bidict==0.13.1
-h5py==2.6.0
-matplotlib==2.0.0
-numpy==1.11.3
-scikit-learn==0.18.1
-scipy==0.18.1
+h5py==2.7.0
+matplotlib==2.0.2
+numpy==1.13.1
+scikit-learn==0.18.2
+scipy==0.19.1
 shortuuid==0.5.0
 six==1.10.0