diff --git a/pyproject.toml b/pyproject.toml
index 4da04acf..8cd27848 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -114,7 +114,8 @@ dependencies = [ # Optional
   "sliderule==4.1.0",
   "ipyleaflet",
   "lmfit",
-  "tables"
+  "tables",
+  "siphon"
 ]
 
 # List additional groups of dependencies   here (e.g. development