diff --git a/.github/workflows/R-CMD-check.yaml b/.github/workflows/R-CMD-check.yaml
index 16e5eaf..b0f691d 100644
--- a/.github/workflows/R-CMD-check.yaml
+++ b/.github/workflows/R-CMD-check.yaml
@@ -68,6 +68,7 @@ jobs:
       - name: Install gsl (windows)
         if: runner.os == 'windows'
         run: |
+          pacman -Sy
           pacman -S mingw-w64-{i686,x86_64}-gsl
         shell: C:\rtools43\usr\bin\bash.EXE --noprofile --norc -e -o pipefail {0}