diff --git a/.github/workflows/cmake-build.yml b/.github/workflows/cmake-build.yml
index 6d01a8ebd6a..d4d5568ec88 100644
--- a/.github/workflows/cmake-build.yml
+++ b/.github/workflows/cmake-build.yml
@@ -40,7 +40,7 @@ jobs:
     - name: Generate CMake options
       shell: bash
       if:  matrix.lib == 'static'
-      run: echo "LIB=-DMAGICK_BUILD_STATIC" >> $GITHUB_ENV
+      run: echo "LIB=-DMAGICK_BUILD_STATIC=1" >> $GITHUB_ENV
 
     - name: Generate CMake build (POSIX)
       run: cd build && cmake .. -DCMAKE_TOOLCHAIN_FILE=conan_toolchain.cmake -DCMAKE_BUILD_TYPE=Release ${{ matrix.lib }} ${{ env.LIB }}