diff --git a/.github/actions/nimbus-build-system/action.yml b/.github/actions/nimbus-build-system/action.yml
index 552b8216..590c5571 100644
--- a/.github/actions/nimbus-build-system/action.yml
+++ b/.github/actions/nimbus-build-system/action.yml
@@ -150,14 +150,13 @@ runs:
       uses: actions/cache@v3
       with:
         path: NimBinaries
-        key: ${{ inputs.os }}-${{ inputs.cpu }}-nim-cache-${{ env.cache_nonce }}-${{ github.run_id }}
-        restore-keys: ${{ inputs.os }}-${{ inputs.cpu }}-nim-cache-${{ env.cache_nonce }}
+        key: ${{ inputs.os }}-${{ inputs.cpu }}-cache-${{ env.cache_nonce }}-${{ github.run_id }}
+        restore-keys: ${{ inputs.os }}-${{ inputs.cpu }}-cache-${{ env.cache_nonce }}
 
     - name: Build Nim and Codex dependencies
       shell: ${{ inputs.shell }} {0}
       run: |
-        . ./env.sh
-        make -j${ncpu} CI_CACHE=NimBinaries ARCH_OVERRIDE=${PLATFORM} QUICK_AND_DIRTY_COMPILER=1 update
+        ./env.sh make -j${ncpu} CI_CACHE=NimBinaries ARCH_OVERRIDE=${PLATFORM} QUICK_AND_DIRTY_COMPILER=1 update
         echo
-        nim --version
+        ./env.sh nim --version
 
diff --git a/env.sh b/env.sh
index 62b8d9f2..f0a7c25b 100755
--- a/env.sh
+++ b/env.sh
@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 
+# This is the compiler version that will get used everywher.
 NIM_VERSION="f45bdea94ac4ed9a9bae03426275456aeb0cab2a"
 NIM_REPO_URL="https://github.com/gmega/Nim"
 
@@ -8,6 +9,16 @@ NIM_REPO_URL="https://github.com/gmega/Nim"
 REL_PATH="$(dirname ${BASH_SOURCE[0]:-${(%):-%x}})"
 ABS_PATH="$(cd ${REL_PATH}; pwd)"
 
+ENV_FILE="${ABS_PATH}/vendor/nimbus-build-system/scripts/env.sh"
+
 export NIM_COMMIT="${NIM_COMMIT:-${NIM_VERSION}}"
-export NIM_REPO="${NIM_REPO_URL:-${NIM_REPO_URL}}"
-source ${ABS_PATH}/vendor/nimbus-build-system/scripts/env.sh
+if ! [ -f "$ENV_FILE" ]; then
+  # Before the first "make update", the env file doesn't exist, so just run
+  # the command that comes after (without a child shell), if any. Running
+  # ./env.sh make update will cause the right compiler to be built right from
+  # the start.
+  echo "Nimbus env file not found"
+  "$@"
+else
+  source "${ENV_FILE}"
+fi