diff --git a/.github/workflows/upstream pretest.yaml b/.github/workflows/upstream pretest.yaml
index e1629952..7e777a34 100644
--- a/.github/workflows/upstream pretest.yaml	
+++ b/.github/workflows/upstream pretest.yaml	
@@ -226,7 +226,7 @@ jobs:
                                             Write-Host "----- HEAD is at $head_sha"
                                         }
                                         
-                                        $old_head_fwd_c = git rev-list --count $sha..HEAD
+                                        $old_head_fwd_c = git rev-list --count "$sha..$head_sha"
                                         if (-not $?) { throw "git rev-list failed" }
                                         
                                         if ($old_head_fwd_c -ne 0) {