diff --git a/arch/Linux-gnu-aarch64-static.ssmp b/arch/Linux-gnu-aarch64-static.ssmp
index c47e933a6d..835a3bdc80 100644
--- a/arch/Linux-gnu-aarch64-static.ssmp
+++ b/arch/Linux-gnu-aarch64-static.ssmp
@@ -2,7 +2,7 @@
 #
 # CP2K (GNU aarch64) arch file for a serial static ARM64 binary
 #
-# Tested with: GNU 14.2.0 and MPICH 4.0.3
+# Tested with: GNU 14.2.0
 #
 # Usage: Source this arch file and then run make as instructed.
 #
diff --git a/arch/Linux-gnu-x86_64.psmp b/arch/Linux-gnu-x86_64.psmp
index eb2dfd43d8..05b74db029 100644
--- a/arch/Linux-gnu-x86_64.psmp
+++ b/arch/Linux-gnu-x86_64.psmp
@@ -2,14 +2,14 @@
 #
 # CP2K (GNU x86_64) arch file for Linux clusters
 #
-# Tested with: GNU 14.2.0, MPICH 4.0.3 and OpenMPI 5.0.6 on the Merlin cluster (PSI)
+# Tested with: GNU 14.2.0, MPICH 4.2.3 and OpenMPI 5.0.6 on the Merlin cluster (PSI)
 #
 # Usage: Source this arch file and then run make as instructed.
 #        A full toolchain installation is performed as default.
 #        Optionally, GNU compiler and MPI implementation can be specified as arguments.
 #        Replace or adapt the "module add" commands below if needed.
 #
-# Last update: 31.12.2024
+# Last update: 06.01.2025
 #
 # \
    if [[ "${0}" == "${BASH_SOURCE}" ]]; then \
diff --git a/tools/toolchain/scripts/stage1/install_mpich.sh b/tools/toolchain/scripts/stage1/install_mpich.sh
index 0a0669bd0f..0a1fa7a5b3 100755
--- a/tools/toolchain/scripts/stage1/install_mpich.sh
+++ b/tools/toolchain/scripts/stage1/install_mpich.sh
@@ -6,8 +6,8 @@
 [ "${BASH_SOURCE[0]}" ] && SCRIPT_NAME="${BASH_SOURCE[0]}" || SCRIPT_NAME=$0
 SCRIPT_DIR="$(cd "$(dirname "$SCRIPT_NAME")/.." && pwd -P)"
 
-mpich_ver="4.0.3"
-mpich_sha256="17406ea90a6ed4ecd5be39c9ddcbfac9343e6ab4f77ac4e8c5ebe4a3e3b6c501"
+mpich_ver="4.2.3"
+mpich_sha256="7a019180c51d1738ad9c5d8d452314de65e828ee240bcb2d1f80de9a65be88a8"
 mpich_pkg="mpich-${mpich_ver}.tar.gz"
 
 source "${SCRIPT_DIR}"/common_vars.sh