diff --git a/requirements.dev.txt b/requirements.dev.txt
index 965b9f4..335a12b 100644
--- a/requirements.dev.txt
+++ b/requirements.dev.txt
@@ -9,7 +9,7 @@ numpy
 pandas>=0.20.1
 pyarrow==0.8.0
 feather-format
-dask
+dask>=0.17.2
 graphviz
 bokeh
 sphinx
@@ -30,3 +30,4 @@ sphinx
 interlap
 loompy
 Pillow>=5.0.0
+distributed>=1.21.6
diff --git a/requirements.txt b/requirements.txt
index 2681d69..5142865 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,19 +1,19 @@
 cytoolz
 multiprocessing_on_dill
-numba==0.37.0
 llvmlite==0.22.0
+numba==0.37.0
 attrs
 frozendict
 numpy
 pandas>=0.20.1
-dask
+cloudpickle
+dask>=0.17.2
+distributed>=1.21.6
+arboretum
 pyarrow==0.8.0
 feather-format
 arboretum
 boltons
-cloudpickle
-distributed
-arboretum
 setuptools
 pyyaml
 tqdm