diff --git a/.github/workflows/validation.yaml b/.github/workflows/validation.yaml
index c50e24841..ba7785b1a 100644
--- a/.github/workflows/validation.yaml
+++ b/.github/workflows/validation.yaml
@@ -208,6 +208,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false
+      max-parallel: 5
       matrix:
         job-purpose: [package, source]
         os: [ubuntu-22.04, ubuntu-24.04, macos-latest, macos-15]
@@ -414,6 +415,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
+      max-parallel: 5
       matrix:
         include:
           - { container: Gentoo, dockerfile: Dockerfile_gentoo }