diff --git a/.github/scripts/util.sh b/.github/scripts/util.sh
index 564dde43b..e97b1963e 100644
--- a/.github/scripts/util.sh
+++ b/.github/scripts/util.sh
@@ -102,8 +102,15 @@ build_ac_xts() {
                 if cc -Werror=unknown-warning-option -Wincompatible-function-pointer-types -c -xc -o /dev/null /dev/null 2>/dev/null; then
                     CFLAGS="$CFLAGS -Wno-error=incompatible-function-pointer-types"
                 fi
+
+                export CFLAGS="$CFLAGS -std=gnu89 \
+                    -Wno-deprecated-non-prototype \
+                    -Wno-pointer-sign \
+                    -Wno-incompatible-pointer-types \
+                    -Wno-implicit-function-declaration \
+                    -Wno-implicit-int"
+
             fi
-            CFLAGS="$CFLAGS -std=gnu89 -Wno-error=implicit-function-declaration -Wno-implicit-int"
             ./autogen.sh --prefix=$X11_PREFIX CFLAGS="$CFLAGS"
             if [ "$X11_OS" = "Darwin" ]; then
                 make -j${FDO_CI_CONCURRENT:-4} install tetexec.cfg