diff --git a/envs/environment_py37_iris30.yml b/envs/environment_py37_iris30.yml
index 05ecbd707e..1a3614cc8e 100644
--- a/envs/environment_py37_iris30.yml
+++ b/envs/environment_py37_iris30.yml
@@ -7,7 +7,7 @@ channels:
 dependencies:
   - python=3.7
   # Required
-  - cartopy
+  - cartopy=0.19
   - cftime<1.5
   - cf-units=2.1.5
   - clize
@@ -21,10 +21,10 @@ dependencies:
   - scipy=1.6
   - sigtools
   - sphinx
+  - statsmodels
   # Optional
   - numba
   - pysteps=1.4.1
-  - statsmodels
   - timezonefinder=4.1.0
   # Development
   - astroid
diff --git a/envs/environment_py38_iris30.yml b/envs/environment_py38_iris30.yml
index a7226124d8..de2ff9b5fd 100644
--- a/envs/environment_py38_iris30.yml
+++ b/envs/environment_py38_iris30.yml
@@ -7,7 +7,7 @@ channels:
 dependencies:
   - python=3.8
   # Required
-  - cartopy
+  - cartopy=0.19
   - cftime<1.5
   - cf-units=2.1.5
   - clize
@@ -21,10 +21,10 @@ dependencies:
   - scipy=1.6
   - sigtools
   - sphinx
+  - statsmodels
   # Optional
   - numba
   - pysteps=1.4.1
-  - statsmodels
   - timezonefinder=4.1.0
   # Development
   - astroid
diff --git a/setup.cfg b/setup.cfg
index 45d2f9a7f5..73a8026068 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -32,6 +32,7 @@ install_requires =
     scitools-iris >= 3.0
     sigtools
     sphinx
+    statsmodels
     stratify
 scripts = bin/improver
 
@@ -55,7 +56,6 @@ dev =
 full =
     numba
     pysteps == 1.3.2
-    statsmodels
     timezonefinder
 
 [flake8]