diff --git a/build/gitlab-ci b/build/gitlab-ci
index a0c4a418..34a550e2 100644
--- a/build/gitlab-ci
+++ b/build/gitlab-ci
@@ -13,7 +13,7 @@ autoconf_build()
     mkdir autoconf-build
     cd autoconf-build
     echo "Running ../configure --prefix=$(pwd)/../autoconf-install) ${opts}"
-    ../configure --prefix=$(pwd)/../autoconf-install ${opts}
+    CFLAGS="-Wall -Wextra -Werror" ../configure --prefix=$(pwd)/../autoconf-install ${opts}
     make
     make install
     make check
@@ -30,7 +30,7 @@ autoconf_build_minimal()
     mkdir autoconf-build
     cd autoconf-build
     echo "Running ../configure --prefix=$(pwd)/../autoconf-install) ${opts}"
-    ../configure --prefix=$(pwd)/../autoconf-install ${opts}
+    CFLAGS="-Wall -Wextra -Werror" ../configure --prefix=$(pwd)/../autoconf-install ${opts}
     make
     make install
     make check
@@ -53,7 +53,7 @@ cmake_build()
         opts2=""
     fi
     echo "Running cmake -G "$1" -DCMAKE_UNITY_BUILD=ON -DCMAKE_BUILD_TYPE="$2" -DCMAKE_INSTALL_PREFIX=../cmake-install ${opts} ${opts2} .."
-    cmake -G "$1" -DCMAKE_UNITY_BUILD=ON -DCMAKE_BUILD_TYPE="$2" -DCMAKE_INSTALL_PREFIX=../cmake-install ${opts} ${opts2}  ..
+    cmake -G "$1" -DCMAKE_UNITY_BUILD=ON -DCMAKE_BUILD_TYPE="$2" -DCMAKE_INSTALL_PREFIX=../cmake-install -DCMAKE_C_FLAGS="-Wall -Wextra -Werror" ${opts} ${opts2}  ..
     $COVERITY_BUILD cmake --build .
     cmake --build . --target install
     ctest -V