diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
index fea509a..a0b5c35 100644
--- a/.github/workflows/unit-tests.yml
+++ b/.github/workflows/unit-tests.yml
@@ -28,7 +28,7 @@ jobs:
                 php-ver: [ '8.3', '8.4' ]
         steps:
             -   name: Set "USE_COVERAGE" env var based on matrix
-                run: echo "USE_COVERAGE=${{ matrix.php-ver == '8.3' }}" >> $GITHUB_ENV
+                run: echo "USE_COVERAGE=${{ ((matrix.php-ver == '8.3') && 'yes') || 'no' }}" >> $GITHUB_ENV
 
             -   name: Checkout
                 uses: actions/checkout@v4
diff --git a/README.md b/README.md
index 30565c0..516e54c 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,8 @@
 
 [![Static Analysis](https://github.com/Toobo/bcp47/actions/workflows/static-analysis.yml/badge.svg)](https://github.com/Toobo/bcp47/actions/workflows/static-analysis.yml)
 [![Unit Tests](https://github.com/Toobo/bcp47/actions/workflows/unit-tests.yml/badge.svg)](https://github.com/Toobo/bcp47/actions/workflows/unit-tests.yml)
-[![Mutation Tests](https://img.shields.io/badge/Mutation_Tests-Min_Covered_MSI_95%25-%2331C553?style=flat&logo=php&logoColor=%23F0F0F0)](https://github.com/Toobo/bcp47/actions/workflows/mutation-tests.yml)
+![Mutation Tests](https://img.shields.io/badge/PHP_8.3%2B-blue?style=flat&logo=php&logoColor=white&labelColor=black)
+[![Mutation Tests](https://img.shields.io/badge/Mutation_Tests-Min_Covered_MSI_95%25-blue?style=flat&logo=php&logoColor=white&labelColor=black)](https://github.com/Toobo/bcp47/actions/workflows/mutation-tests.yml)
 
 ---