Try different variable syntax.
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 505a2a5..14aba87 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -21,9 +21,9 @@
       - name: configure
         working-directory: ${{runner.workspace}}/build
         run: |
-          echo running .....cmake $GITHUB_WORKSPACE .....
+          echo running .....cmake ${{github.workspace}} .....
           echo working directory ${{runner.workspace}}/build
-          cmake $GITHUB_WORKSPACE
+          cmake ${{github.workspace}}
       - name: build
         working-directory: ${{runner.workspace}}/build
         run: |