diff --git a/.github/workflows/docker-image.yml b/.github/workflows/docker-image.yml
index 87b0cad..3d2e379 100644
--- a/.github/workflows/docker-image.yml
+++ b/.github/workflows/docker-image.yml
@@ -28,7 +28,7 @@ jobs:
       - name: Resolve upstream version
         id: version
         run: |
-          rev=$(rg -o 'rev\s*=\s*"[^"]+"' nix/sources/clawdbot-source.nix | head -n 1 | sed -E 's/.*"([^"]+)".*/\1/')
+          rev=$(grep -E 'rev\s*=\s*"' nix/sources/clawdbot-source.nix | head -n 1 | sed -E 's/.*"([^"]+)".*/\1/')
           if [ -z "$rev" ]; then
             echo "rev not found in nix/sources/clawdbot-source.nix" >&2
             exit 1