diff --git a/build-push/bin/build-push.sh b/build-push/bin/build-push.sh
index 7d9d3bb..984bf7a 100755
--- a/build-push/bin/build-push.sh
+++ b/build-push/bin/build-push.sh
@@ -256,7 +256,7 @@ parse_args() {
 BUILTIID=""    # populated with the image-id on successful build
 parallel_build() {
     local arch
-    local platforms
+    local platforms=""
     local build="bud"
     local output
     local _fqin
@@ -268,7 +268,7 @@ parallel_build() {
 
 
     for arch in "${ARCHES[@]}"; do
-        platforms="${platforms:+$platforms }--platform=$PLATFORMOS/$arch"
+        platforms="${platforms:+$platforms,}$PLATFORMOS/$arch"
     done
 
     # Keep user-specified BUILD_ARGS near the beginning so errors are easy to spot
@@ -277,7 +277,7 @@ parallel_build() {
              "${BUILD_ARGS[@]}" \
               --layers --force-rm \
               --jobs="$PARALLEL_JOBS" \
-              $platforms \
+              --platform=$platforms \
               --manifest="$_fqin" \
               "$CONTEXT" |& tee /dev/stderr)
     BUILDIID=$(tail -1 <<<"$output")