diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index f012edef..5c087573 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -25,13 +25,13 @@ env:
 
 jobs:
   build:
-    runs-on: ${{ matrix.os }}
 
     strategy:
       fail-fast: false
       matrix:
-        os: [  env.UBUNTU_VERSION  , windows-2019, macos-latest ]
+        os: [ ${{ env.UBUNTU_VERSION }} , windows-2019, macos-latest ]
 
+    runs-on: ${{ matrix.os }}
     steps:
 
       - name: Set up Java