diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 44f7eb2289b..b76145944ce 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -10,7 +10,8 @@ env:
     # These must be set for fetchdep.sh to get the right branch
     REPOSITORY: ${{ github.repository }}
     PR_NUMBER: ${{ github.event.pull_request.number }}
-    COMMIT_SHA: ${{ github.event.pull_request.head.sha }}
+    PR_COMMIT_SHA: ${{ github.event.pull_request.head.sha }}
+    GH_COMMIT_SHA: ${{ github.sha }}
 permissions: {} # No permissions required
 jobs:
     build:
diff --git a/scripts/get-version-from-git.sh b/scripts/get-version-from-git.sh
index 8641ab0ca51..1bc21a7b148 100755
--- a/scripts/get-version-from-git.sh
+++ b/scripts/get-version-from-git.sh
@@ -9,4 +9,10 @@ set -e
 JSSDK_SHA=$(git -C node_modules/matrix-js-sdk rev-parse --short=7 HEAD)
 #VECTOR_SHA=$(git rev-parse --short=7 HEAD) # use the ACTUAL SHA rather than assume develop
 #echo $VECTOR_SHA-js-$JSSDK_SHA
+
+# set the version SHA to the PR commit SHA if we're in a PR
+# or use the latest main branch commit SHA if we're in a push
+COMMIT_SHA=${COMMIT_SHA:-$GH_COMMIT_SHA}
+[ -n "$PR_COMMIT_SHA" ] && COMMIT_SHA=$PR_COMMIT_SHA
+
 echo "${COMMIT_SHA:0:7}-js-$JSSDK_SHA"