diff --git a/spack-environment/packages.yaml b/spack-environment/packages.yaml
index c3195420b0e52f7dd07e232ba35395cd3f764563..b053344be04b7171a37a531f9bdddabbf7b96d27 100644
--- a/spack-environment/packages.yaml
+++ b/spack-environment/packages.yaml
@@ -182,7 +182,7 @@ packages:
     - +python +rootio
   hepmcmerger:
     require:
-    - '@1.0.4'
+    - '@1.0.5'
   heppdt:
     require:
     - '@2.06.01'