diff --git a/scripts/azure-pipelines/test-modified-ports.ps1 b/scripts/azure-pipelines/test-modified-ports.ps1
index 55a05aef32..a34f2f416d 100755
--- a/scripts/azure-pipelines/test-modified-ports.ps1
+++ b/scripts/azure-pipelines/test-modified-ports.ps1
@@ -136,6 +136,8 @@ if ($LASTEXITCODE -ne 0)
 $parentHashes = @()
 if (($BuildReason -eq 'PullRequest') -and -not $NoParentHashes)
 {
+    $headBaseline = Get-Content "$PSScriptRoot/../ci.baseline.txt" -Raw
+
     # Prefetch tools for better output
     foreach ($tool in @('cmake', 'ninja', 'git')) {
         & "./vcpkg$executableExtension" fetch $tool
@@ -145,17 +147,25 @@ if (($BuildReason -eq 'PullRequest') -and -not $NoParentHashes)
         }
     }
 
-    Write-Host "Determining parent hashes using HEAD~1"
-    $parentHashesFile = Join-Path $ArtifactStagingDirectory 'parent-hashes.json'
-    $parentHashes = @("--parent-hashes=$parentHashesFile")
+    Write-Host "Comparing with HEAD~1"
     & git revert -n -m 1 HEAD | Out-Null
-    # The vcpkg.cmake toolchain file is not part of ABI hashing,
-    # but changes must trigger at least some testing.
-    Copy-Item "scripts/buildsystems/vcpkg.cmake" -Destination "scripts/test_ports/cmake"
-    Copy-Item "scripts/buildsystems/vcpkg.cmake" -Destination "scripts/test_ports/cmake-user"
-    & "./vcpkg$executableExtension" ci "--triplet=$Triplet" --dry-run "--ci-baseline=$PSScriptRoot/../ci.baseline.txt" @commonArgs --no-binarycaching "--output-hashes=$parentHashesFile"
-
-    Write-Host "Running CI using parent hashes"
+    $parentBaseline = Get-Content "$PSScriptRoot/../ci.baseline.txt" -Raw
+    if ($parentBaseline -eq $headBaseline)
+    {
+        Write-Host "CI baseline unchanged, determining parent hashes"
+        $parentHashesFile = Join-Path $ArtifactStagingDirectory 'parent-hashes.json'
+        $parentHashes = @("--parent-hashes=$parentHashesFile")
+        # The vcpkg.cmake toolchain file is not part of ABI hashing,
+        # but changes must trigger at least some testing.
+        Copy-Item "scripts/buildsystems/vcpkg.cmake" -Destination "scripts/test_ports/cmake"
+        Copy-Item "scripts/buildsystems/vcpkg.cmake" -Destination "scripts/test_ports/cmake-user"
+        & "./vcpkg$executableExtension" ci "--triplet=$Triplet" --dry-run "--ci-baseline=$PSScriptRoot/../ci.baseline.txt" @commonArgs --no-binarycaching "--output-hashes=$parentHashesFile"
+    }
+    else
+    {
+        Write-Host "CI baseline was modified, not using parent hashes"
+    }
+    Write-Host "Running CI for HEAD"
     & git reset --hard HEAD
 }