diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 66c2eccc..c67c1a8d 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -48,7 +48,7 @@ jobs:
           needs: check
 
       - name: Build CMTK
-        if: matrix.os != 'windows-latest'
+        if: ${{matrix.config.os != 'windows-latest'}}
         run: sh ./build-cmtk.sh
         env:
           MAKEFLAGS: "-j2"