diff --git a/pyproject.toml b/pyproject.toml
index 5c8b5d8a55d..20817b4ea05 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,6 +49,7 @@ dependencies = [
     "matplotlib",
     "netCDF4",
     "numpy<2",
+    "openpyxl",  # extra dependency for pandas (excel)
     "orjson",
     "packaging",
     "pandas",