diff --git a/.github/workflows/build_openmpi_source.yml b/.github/workflows/build_openmpi_source.yml
index ce5f6d1b4c3..92ad5b055cb 100644
--- a/.github/workflows/build_openmpi_source.yml
+++ b/.github/workflows/build_openmpi_source.yml
@@ -1,14 +1,11 @@
 # Build OpenMPI from source using the latest commit on the
-# 'main' branch and cache the results
+# 'main' branch and cache the results. Result is installed
+# to (or restored to) '${{ github.workspace }}/openmpi'.
 
 # Triggers the workflow on a call from another workflow
 on:
   workflow_call:
     inputs:
-      install_path:
-        description: "location to install OpenMPI to or restore to from cache"
-        required: true
-        type: string
       build_mode:
         description: "production vs. debug build"
         required: true
@@ -24,12 +21,12 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - name: Install Linux Dependencies
+      - name: Install Linux dependencies
         run: |
           sudo apt-get update
           sudo apt-get install build-essential libtool libtool-bin
 
-      - name: Get OpenMPI Source
+      - name: Get OpenMPI source
         uses: actions/checkout@v4.1.7
         with:
           repository: 'open-mpi/ompi'
@@ -51,8 +48,8 @@ jobs:
         id: cache-openmpi-ubuntu-gcc
         uses: actions/cache@v4
         with:
-          path: ${{ inputs.install_path }}
-          key: ${{ runner.os }}-${{ runner.arch }}-gcc-openmpi-${{ steps.get-sha.outputs.sha }}
+          path: ${{ github.workspace }}/openmpi
+          key: ${{ runner.os }}-${{ runner.arch }}-gcc-openmpi-${{ steps.get-sha.outputs.sha }}-${{ inputs.build_mode }}
 
       - name: Install OpenMPI (GCC) (Production)
         if: ${{ steps.cache-openmpi-ubuntu-gcc.cache-hit != 'true' && (inputs.build_mode != 'debug') }}
@@ -61,7 +58,7 @@ jobs:
           ./autogen.pl
           ./configure \
             CC=gcc \
-            --prefix=${{ inputs.install_path }}
+            --prefix=${{ github.workspace }}/openmpi
           make -j2
           make install
 
@@ -72,7 +69,7 @@ jobs:
           ./autogen.pl
           ./configure \
             CC=gcc \
-            --prefix=${{ inputs.install_path }} \
+            --prefix=${{ github.workspace }}/openmpi \
             --enable-debug
           make -j2
           make install
diff --git a/.github/workflows/test_build_openmpi_source.yml b/.github/workflows/test_build_openmpi_source.yml
index 0aa828df99c..60b65f56853 100644
--- a/.github/workflows/test_build_openmpi_source.yml
+++ b/.github/workflows/test_build_openmpi_source.yml
@@ -11,5 +11,4 @@ jobs:
     name: "OpenMPI debug"
     uses: ./.github/workflows/build_openmpi_source.yml
     with:
-      install_path: ${{ github.workspace }}/openmpi_install
       build_mode: "debug"
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