diff --git a/install_spack_env.sh b/install_spack_env.sh
index b354b43b923b7342bcfb460abcbbdaa9d744fcf7..f0065f9888b9bfb93d811e327ce12627d5b49ec4 100644
--- a/install_spack_env.sh
+++ b/install_spack_env.sh
@@ -77,6 +77,12 @@ rm $SPACK_ROOT/var/spack/environments/$EBRAINS_SPACK_ENV/spack.lock || echo "No
 
 # activate environment
 spack env activate $EBRAINS_SPACK_ENV
+
+# fetch all sources
+spack concretize --fresh --test root
+spack fetch --dependencies --missing
+rm $SPACK_ROOT/var/spack/environments/$EBRAINS_SPACK_ENV/spack.lock
+
 # install the environment, use 2 jobs to reduce the amount of required RAM
 spack install -y -j2 --fresh --test root