diff --git a/environments/hlrs/spack.yaml b/environments/hlrs/spack.yaml
index dde7206..858d80a 100644
--- a/environments/hlrs/spack.yaml
+++ b/environments/hlrs/spack.yaml
@@ -4,6 +4,7 @@ spack:
     - core_compiler: [gcc@7.5]
     - compilers: [gcc@13.2, cce@18.0]
     - mpis: [cray-mpich@8.1.30]
+    - cflags_noerror_implicit: ['cflags="-Wno-error=implicit-function-declaration -Wno-error=implicit-int -Wno-error=int-conversion"']
   packages:
     all:
       prefer: ['%gcc@7.5']
@@ -14,7 +15,7 @@ spack:
       - [$%core_compiler]
     - matrix:
       - [mpip, extrae]
-      - ['cflags="-Wno-error=implicit-function-declaration -Wno-error=implicit-int -Wno-error=int-conversion"']
+      - [$cflags_noerror_implicit]    # code is not fully C99
       - [$^mpis]
       - [$%compilers]
   view: false