diff --git a/.python-version b/.python-version
new file mode 100644
index 0000000..424e179
--- /dev/null
+++ b/.python-version
@@ -0,0 +1 @@
+3.6.8
diff --git a/requirements.sh b/requirements.sh
deleted file mode 100755
index fd2880e..0000000
--- a/requirements.sh
+++ /dev/null
@@ -1,27 +0,0 @@
-#!/bin/bash
-
-set -e
-
-if conda --version >/dev/null 2>&1
-then
-    conda install \
-          astropy=3.0.1 \
-          beautifulsoup4=4.6.0 \
-          html5lib=1.0.1 \
-          lxml=4.2.1 \
-          mock=2.0.0 \
-          numpy=1.14.2 \
-          pandas=0.23.3 \
-          python=3.6 \
-          pytz \
-          sphinx=1.7.2 \
-
-else
-    if ! python --version 2>&1 | grep -q 2.6
-    then pip install astropy
-    fi
-    pip install mock numpy sphinx pytz
-fi
-pip install de405==1997.1 de423==2010.1
-pip install https://github.com/brandon-rhodes/assay/archive/master.zip
-pip install -e .
diff --git a/requirements.txt b/requirements.txt
new file mode 100755
index 0000000..5ce8bf2
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,11 @@
+astropy==3.2.2
+beautifulsoup4==4.6.0
+html5lib==1.0.1
+lxml==4.4.1
+mock==2.0.0
+numpy==1.14.2
+pandas==0.23.3
+pytz
+sphinx==1.7.2
+https://github.com/brandon-rhodes/assay/archive/master.zip
+-e .