diff --git a/.github/workflows/boxes.yml b/.github/workflows/boxes.yml
index 58c6e38..8853e22 100644
--- a/.github/workflows/boxes.yml
+++ b/.github/workflows/boxes.yml
@@ -48,6 +48,11 @@ jobs:
 
     build-mac:
         runs-on: macos-latest
+        env:
+          LANG: C
+          LC_ALL: C
+          LEX: /usr/local/opt/flex/bin/flex
+          YACC: /usr/local/opt/bison/bin/bison
         steps:
             - uses: actions/checkout@v3
 
@@ -60,15 +65,15 @@ jobs:
                   echo '/usr/local/opt/findutils/libexec/gnubin' >> $GITHUB_PATH
 
             - name: make cov
-              run: make cov LEX=/usr/local/opt/flex/bin/flex YACC=/usr/local/opt/bison/bin/bison
+              run: make cov
 
             # This uses ld --wrap to mock the cmocka functions but
             # macOS ld does not support --wrap
             #- name: Run white-box tests
-              #run: make utest LEX=/usr/local/opt/flex/bin/flex YACC=/usr/local/opt/bison/bin/bison
+              #run: make utest
 
             - name: Run black-box tests
-              run: make covtest LEX=/usr/local/opt/flex/bin/flex YACC=/usr/local/opt/bison/bin/bison
+              run: make covtest
 
             - name: Coveralls
               uses: coverallsapp/github-action@v2