diff --git a/actions/setup/action.yaml b/actions/setup/action.yaml
index b41783f9..9df428c7 100644
--- a/actions/setup/action.yaml
+++ b/actions/setup/action.yaml
@@ -219,12 +219,13 @@ runs:
         # Install extra packages to to Packages/<Package>
         PC_PACKAGES=""
         while read -r x; do
-            if [[ "$x" =~ ^(.*):(.*)/([^@]*)@?(.*)$ ]]; then
+            # The ref is everything after the first `@`, so that it can contain `/`, e.g. `feat/foo`.
+            if [[ "$x" =~ ^([^:/]+):([^/]+)/([^@]+)@?(.*)$ ]]; then
                 PKG="${BASH_REMATCH[1]}"
                 USER="${BASH_REMATCH[2]}"
                 REPO="${BASH_REMATCH[3]}"
                 SHA="${BASH_REMATCH[4]}"
-            elif [[ "$x" =~ ^(.*)/([^@]*)@?(.*)$ ]]; then
+            elif [[ "$x" =~ ^([^/]+)/([^@]+)@?(.*)$ ]]; then
                 PKG="${BASH_REMATCH[2]}"
                 USER="${BASH_REMATCH[1]}"
                 REPO="${BASH_REMATCH[2]}"