diff --git a/conda_env.yml b/conda_env.yml
index e61979a6..8b15adb5 100644
--- a/conda_env.yml
+++ b/conda_env.yml
@@ -3,7 +3,7 @@
 
 name: gprMax
 dependencies:
-- python>=3.4
+- python=3.6.*
 - colorama
 - cython
 - h5py