diff --git a/.github/workflows/wheels-test.sh b/.github/workflows/wheels-test.sh
index ab8de3dc9c4..f2c74dcd411 100755
--- a/.github/workflows/wheels-test.sh
+++ b/.github/workflows/wheels-test.sh
@@ -8,12 +8,12 @@ EXP_FEATURES="fribidi harfbuzz libjpeg_turbo raqm transp_webp webp_anim webp_mux
 if [[ "$OSTYPE" == "darwin"* ]]; then
     brew install fribidi
     export PKG_CONFIG_PATH="/usr/local/opt/openblas/lib/pkgconfig"
-elif [ "${AUDITWHEEL_POLICY:9}" == "musllinux" ]; then
+elif [ "${AUDITWHEEL_POLICY::9}" == "musllinux" ]; then
     apk add curl fribidi
 else
     yum install -y fribidi openblas-devel pkgconfig
 fi
-if [ "${AUDITWHEEL_POLICY:9}" != "musllinux" ]; then
+if [ "${AUDITWHEEL_POLICY::9}" != "musllinux" ]; then
     python3 -m pip install numpy
 fi
 
diff --git a/pyproject.toml b/pyproject.toml
index ba11096fa0d..70572b99435 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -82,9 +82,6 @@ before-all = ".github/workflows/wheels-dependencies.sh"
 test-command = "cd {project} && .github/workflows/wheels-test.sh"
 test-extras = "tests"
 
-[tool.cibuildwheel.linux]
-environment = { CFLAGS="--std=c99" }
-
 [tool.ruff]
 line-length = 88
 select = [