diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 08cb3af10..52b79fda4 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -19,6 +19,10 @@ jobs:
       - run: echo "This job is now running on a ${{ runner.os }} server hosted by GitHub!"
       - run: echo "The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
 
+      - name: Installling Open MPI
+        run: |
+          sudo apt-get install -y libopenmpi-dev
+
       - name: Installing MATLAB
         id:   setup-matlab
         uses: matlab-actions/setup-matlab@v2
@@ -28,6 +32,11 @@ jobs:
       - name: Check out repository code
         uses: actions/checkout@v4
 
+      - name: Modify PETSc's installation script
+        run: |
+          echo "Removing mpich from PETSc installation script"
+          sed -i.bak '/mpich/d' $ISSM_DIR/externalpackages/petsc/install-3.21-linux.sh
+
       - name: Install External packages
         run: |
           cd $ISSM_DIR/externalpackages/triangle && ./install-linux.sh
@@ -45,8 +54,8 @@ jobs:
           --with-numthreads=4 \
           --with-matlab-dir=${{ steps.setup-matlab.outputs.matlabroot }} \
           --with-fortran-lib="-L/usr/lib/x86_64-linux-gnu -lgfortran" \
-          --with-mpi-include="${ISSM_DIR}/externalpackages/petsc/install/include" \
-          --with-mpi-libflags="-L${ISSM_DIR}/externalpackages/petsc/install/lib -lmpi -lmpicxx -lmpifort" \
+          --with-mpi-include="/usr/lib/x86_64-linux-gnu/openmpi/include/" \
+          --with-mpi-libflags="-L/usr/lib/x86_64-linux-gnu/openmpi/lib -lmpi -lmpi_cxx" \
           --with-petsc-dir="${ISSM_DIR}/externalpackages/petsc/install" \
           --with-blas-lapack-dir="${ISSM_DIR}/externalpackages/petsc/install" \
           --with-metis-dir="${ISSM_DIR}/externalpackages/petsc/install" \
diff --git a/externalpackages/petsc/install-3.21-andes.sh b/externalpackages/petsc/install-3.21-andes.sh
index a5d41e24d..095309099 100755
--- a/externalpackages/petsc/install-3.21-andes.sh
+++ b/externalpackages/petsc/install-3.21-andes.sh
@@ -2,7 +2,7 @@
 set -eu
 
 ## Constants
-VER="3.21.2"
+VER="3.21.3"
 
 PETSC_DIR="${ISSM_DIR}/externalpackages/petsc/src" # DO NOT CHANGE THIS
 PREFIX="${ISSM_DIR}/externalpackages/petsc/install" # Set to location where external package should be installed
diff --git a/externalpackages/petsc/install-3.21-linux.sh b/externalpackages/petsc/install-3.21-linux.sh
index 9f6cc8a95..b6d7a0498 100755
--- a/externalpackages/petsc/install-3.21-linux.sh
+++ b/externalpackages/petsc/install-3.21-linux.sh
@@ -3,7 +3,7 @@ set -eu
 
 ## Constants
 #
-VER="3.21.2"
+VER="3.21.3"
 
 PETSC_DIR="${ISSM_DIR}/externalpackages/petsc/src" # DO NOT CHANGE THIS
 PREFIX="${ISSM_DIR}/externalpackages/petsc/install" # Set to location where external package should be installed
diff --git a/externalpackages/petsc/install-3.21-mac.sh b/externalpackages/petsc/install-3.21-mac.sh
index 9f6cc8a95..f3e2012f4 100755
--- a/externalpackages/petsc/install-3.21-mac.sh
+++ b/externalpackages/petsc/install-3.21-mac.sh
@@ -3,7 +3,7 @@ set -eu
 
 ## Constants
 #
-VER="3.21.2"
+VER="3.21.3"
 
 PETSC_DIR="${ISSM_DIR}/externalpackages/petsc/src" # DO NOT CHANGE THIS
 PREFIX="${ISSM_DIR}/externalpackages/petsc/install" # Set to location where external package should be installed
@@ -28,7 +28,7 @@ cd ${PETSC_DIR}
 	--prefix="${PREFIX}" \
 	--PETSC_DIR="${PETSC_DIR}" \
 	--CFLAGS="-g -O2" --CXXFLAGS="-g -O2" --FFLAGS="-g -O2" \
-	--with-debugging=0 \
+	--with-debugging=1 \
 	--with-valgrind=0 \
 	--with-x=0 \
 	--with-ssl=0 \