diff --git a/.github/workflows/build-linux.yml b/.github/workflows/build-linux.yml
index 3da91037e01..879d07bec20 100644
--- a/.github/workflows/build-linux.yml
+++ b/.github/workflows/build-linux.yml
@@ -37,6 +37,7 @@ jobs:
             echo FSTAR_VERSION="nightly-$(date -I)" >> $GITHUB_ENV
           elif [[ "${{github.workflow_ref}}" =~ "release.yml" ]]; then
             echo FSTAR_VERSION="$(cat version.txt)" >> $GITHUB_ENV
+            echo FSTAR_RELEASE=1 >> $GITHUB_ENV
           fi
 
       # NB: release workflow later adds version number to the name
diff --git a/.github/workflows/build-macos.yml b/.github/workflows/build-macos.yml
index 6c9863cc302..4a9d2748e00 100644
--- a/.github/workflows/build-macos.yml
+++ b/.github/workflows/build-macos.yml
@@ -29,6 +29,7 @@ jobs:
             echo FSTAR_VERSION="nightly-$(date -I)" >> $GITHUB_ENV
           elif [[ "${{github.workflow_ref}}" =~ "release.yml" ]]; then
             echo FSTAR_VERSION="$(cat version.txt)" >> $GITHUB_ENV
+            echo FSTAR_RELEASE=1 >> $GITHUB_ENV
           fi
 
       # Note *g*make below!
diff --git a/.scripts/mk-package.sh b/.scripts/mk-package.sh
index 7d37bed1062..7a02148b960 100755
--- a/.scripts/mk-package.sh
+++ b/.scripts/mk-package.sh
@@ -32,6 +32,10 @@ windows () {
   [[ "${OS:-}" = "Windows_NT" ]]
 }
 
+release () {
+  [[ -n "${FSTAR_RELEASE:-}" ]]
+}
+
 # Computes a (hopefully) sensible default for the current system
 detect_format () {
   if windows; then
@@ -67,7 +71,7 @@ case $FSTAR_PACKAGE_FORMAT in
     ATGT="$(realpath "$TGT")"
     pushd "$PREFIX" >/dev/null
     LEVEL=
-    if [ -v FSTAR_RELEASE ]; then
+    if release; then
       LEVEL=-9
     fi
     $WRAP zip -q -r $LEVEL "$ATGT" .
@@ -77,7 +81,7 @@ case $FSTAR_PACKAGE_FORMAT in
     TGT="$ARCHIVE.zip"
     ATGT="$(realpath "$TGT")"
     LEVEL=
-    if [ -v FSTAR_RELEASE ]; then
+    if release; then
       LEVEL=-mx9
     fi
     pushd "$PREFIX" >/dev/null
@@ -89,7 +93,7 @@ case $FSTAR_PACKAGE_FORMAT in
     TGT="$ARCHIVE.tar.gz"
     $WRAP tar cf "$ARCHIVE.tar" -h -C "$PREFIX" .
     LEVEL=
-    if [ -v FSTAR_RELEASE ]; then
+    if release; then
       LEVEL=-9
     fi
     $WRAP gzip -f $LEVEL "$ARCHIVE.tar"