diff --git a/environment.yml b/environment.yml
index 4281067ccd..9bd0a1f0b6 100755
--- a/environment.yml
+++ b/environment.yml
@@ -6,5 +6,5 @@ dependencies:
   - python=2.7
   - pip
   - pip:
-    - mkdocs-unidata
+    - mkdocs-unidata==1.5.7
     - fontawesome_markdown