diff --git a/spack.yaml b/spack.yaml
index 8d86322ab099575187dfe3b14199ebfd9c131d48..d8b25eb96bcf92935fc4041c9c8d50515bfee031 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -4,6 +4,7 @@ spack:
     - cairo@1.16.0 +fc+ft+X+pdf+gobject
     - clhep@2.4.4.0 cxxstd=17
     - cmake@3.21.4
+    - cnpy@master
     - dawn@3_91a
     - dawncut@1_54a
     - dd4hep@1.20.1 +geant4 -assimp +hepmc3 +ipo +lcio