diff --git a/requirements.txt b/requirements.txt
index c8a3d79..b996262 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1,2 @@
 pyam-iamc>=1.0  # the pyam package is released on pypi.org under this name
-nomenclature-iamc >= 0.9
+nomenclature-iamc >= 0.18.1