diff --git a/tools/ci.psm1 b/tools/ci.psm1
index 73c6cb41e8..6628d54e04 100644
--- a/tools/ci.psm1
+++ b/tools/ci.psm1
@@ -863,11 +863,17 @@ function Invoke-InitializeContainerStage {
 
     # For PRs set the seed to the PR number so that the image is always the same
     $seed = $env:SYSTEM_PULLREQUEST_PULLREQUESTID
+
     if(!$seed) {
       # for non-PRs use the integer identifier of the build as the seed.
       $seed = $fallbackSeed
     }
 
+    # cut down to 32 bits and keep the most varying parts, which are lower bits
+    if ($seed -ge [Int32]::MaxValue) {
+        $seed = [int]($seed -band [int]::MaxValue)
+    }
+
     Write-Verbose "Seed: $seed" -Verbose
 
     # Get the latest image matrix JSON for preview