diff --git a/env/merlin/spack.yaml b/env/merlin/spack.yaml
index 4d8638e..70e98b9 100644
--- a/env/merlin/spack.yaml
+++ b/env/merlin/spack.yaml
@@ -164,7 +164,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/Batchsystem
+        tcl: &Batchsystem_module_root /afs/psi.ch/sys/spack-rhel7/Batchsystem
       tcl:
         blacklist_implicits: true
         include: *Batchsystem_pckgs
@@ -173,6 +173,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *Batchsystem_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -207,7 +209,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/cuda
+        tcl: &Cuda_module_root /afs/psi.ch/sys/spack-rhel7/cuda
       tcl:
         blacklist_implicits: true
         include: *Cuda_pckgs
@@ -216,6 +218,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *Cuda_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -227,7 +231,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/EM
+        tcl: &EM_module_root /afs/psi.ch/sys/spack-rhel7/EM
       tcl:
         blacklist_implicits: true
         include: *EM_pckgs
@@ -236,6 +240,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *EM_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -247,7 +253,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/HDF5
+        tcl: &HDF5_module_root /afs/psi.ch/sys/spack-rhel7/HDF5
       tcl:
         blacklist_implicits: true
         include: *HDF5_pckgs
@@ -257,6 +263,8 @@ spack:
             - '{name}'
             - 'HDF5_serial'
           environment:
+            append_path:
+              MODULEPATH: *HDF5_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -268,7 +276,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/HDF5_serial
+        tcl: &HDF5_serial_module_root /afs/psi.ch/sys/spack-rhel7/HDF5_serial
       tcl:
         blacklist_implicits: true
         include: *HDF5_serial_pckgs
@@ -278,6 +286,8 @@ spack:
             - '{name}'
             - 'HDF5_serial'
           environment:
+            append_path:
+              MODULEPATH: *HDF5_serial_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -289,7 +299,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/Librairies
+        tcl: &Librairies_module_root /afs/psi.ch/sys/spack-rhel7/Librairies
       tcl:
         blacklist_implicits: true
         include: *Librairies_pckgs
@@ -298,6 +308,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *Librairies_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -309,7 +321,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/MPI
+        tcl: &MPI_module_root /afs/psi.ch/sys/spack-rhel7/MPI
       tcl:
         blacklist_implicits: true
         include: *MPI_pckgs
@@ -318,6 +330,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *MPI_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -329,7 +343,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/MX
+        tcl: &MX_module_root /afs/psi.ch/sys/spack-rhel7/MX
       tcl:
         blacklist_implicits: true
         include: *MX_pckgs
@@ -338,6 +352,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *MX_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -349,7 +365,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/Programming
+        tcl: &Programming_module_root /afs/psi.ch/sys/spack-rhel7/Programming
       tcl:
         blacklist_implicits: true
         include: *Programming_pckgs
@@ -358,6 +374,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *Programming_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -369,7 +387,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/System
+        tcl: &System_module_root /afs/psi.ch/sys/spack-rhel7/System
       tcl:
         blacklist_implicits: true
         include: *System_pckgs
@@ -378,6 +396,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *System_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'
@@ -389,7 +409,7 @@ spack:
       enable:
       - tcl
       roots:
-        tcl: /afs/psi.ch/sys/spack-rhel7/Tools
+        tcl: &Tools_module_root /afs/psi.ch/sys/spack-rhel7/Tools
       tcl:
         blacklist_implicits: true
         include: *Tools_pckgs
@@ -398,6 +418,8 @@ spack:
           conflict:
             - '{name}'
           environment:
+            append_path:
+              MODULEPATH: *Tools_module_root
             set:
               ${PACKAGE}_INCLUDE_DIR: '{prefix}/include'
               ${PACKAGE}_LIBRARY_DIR: '{prefix}/lib'