diff --git a/.github/workflows/quickstart.yml b/.github/workflows/quickstart.yml
index ad1372b..82c8382 100644
--- a/.github/workflows/quickstart.yml
+++ b/.github/workflows/quickstart.yml
@@ -18,7 +18,7 @@ jobs:
       - id: setup-matrix
         uses: druzsan/setup-matrix@feature/use-python-dockerfile
         with:
-          matrix: |
+          matrix: | # Use | to preserve valid YAML syntax
             fruit: [apple, pear]
             animal: [quick red fox, lazy dog]
             include:
@@ -29,7 +29,7 @@ jobs:
                 animal: cat
             exclude:
               - fruit: apple
-                animal: lazy dog
+                animal: lazy dog # Any comment
   # Setup python and print version
   echo:
     needs: setup-matrix
diff --git a/README.md b/README.md
index cf7fe88..bdfce47 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@ For more examples, see [advanced usage](#advanced-usage)
 
 ## Inputs
 
-Action has only one input `matrix`, whose syntax is exactly the same as the built-in matrix provided as string (limitation of custom GitHub actions).
+Action has only one required input `matrix`, whose syntax is exactly the same as the built-in matrix provided as string (limitation of custom GitHub actions).
 
 ```yaml
 with: