diff --git a/configs/sites/hercules/packages.yaml b/configs/sites/hercules/packages.yaml
index 1ee04592a..ba90ee657 100644
--- a/configs/sites/hercules/packages.yaml
+++ b/configs/sites/hercules/packages.yaml
@@ -23,7 +23,7 @@ packages:
 
 ### Modifications of common packages
   # Version 2.0.5 doesn't compile on Hercules with gcc
-  cdo
+  cdo:
     version:: ['2.2.0']
   # Version 2.0.8 doesn't compile on Hercules
   wgrib2: