diff --git a/requirements.txt b/requirements.txt
index b7ae6de..aaf7c6c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,8 +1,8 @@
-numpy
-astropy
-scipy
+numpy==1.13.1
+astropy==2.0.2
+scipy==0.19.1
 #pyastronomy
-hypothesis
-pytest
-pytest-cov
-python-coveralls
+hypothesis==3.30.1
+pytest==3.2.2
+pytest-cov==2.5.1
+python-coveralls==2.9.1