diff --git a/.github/workflows/ode-toolbox-build.yml b/.github/workflows/ode-toolbox-build.yml
index 4c929cdc..2ac32a01 100644
--- a/.github/workflows/ode-toolbox-build.yml
+++ b/.github/workflows/ode-toolbox-build.yml
@@ -60,7 +60,7 @@ jobs:
           sudo apt install pkg-config python3-all-dev
 
       - name: Install GSL
-        if: ${{ matrix.with_gsl }} == "1"
+        if: ${{ matrix.with_gsl == '1' }}
         run: |
           sudo apt remove libgsl27 libgsl-dev    # remove system-wide GSL version that is installed by default
           cd ..