diff --git a/.ci/linux-build.sh b/.ci/linux-build.sh
index 99850a943..8227a5748 100755
--- a/.ci/linux-build.sh
+++ b/.ci/linux-build.sh
@@ -82,6 +82,10 @@ if [ "$DPDK" ] || [ "$DPDK_SHARED" ]; then
     install_dpdk
 fi
 
+if [ "$STD" ]; then
+    CFLAGS_FOR_OVS="${CFLAGS_FOR_OVS} -std=$STD"
+fi
+
 if [ "$CC" = "clang" ]; then
     CFLAGS_FOR_OVS="${CFLAGS_FOR_OVS} -Wno-error=unused-command-line-argument"
 elif [ "$M32" ]; then
diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index 47d239f10..bc5494e86 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -85,6 +85,7 @@ jobs:
       LIBS:        ${{ matrix.libs }}
       M32:         ${{ matrix.m32 }}
       OPTS:        ${{ matrix.opts }}
+      STD:         ${{ matrix.std }}
       TESTSUITE:   ${{ matrix.testsuite }}
 
     name: linux ${{ join(matrix.*, ' ') }}
@@ -100,6 +101,11 @@ jobs:
           - compiler:     clang
             opts:         --disable-ssl
 
+          - compiler:     gcc
+            std:          c99
+          - compiler:     clang
+            std:          c99
+
           - compiler:     gcc
             testsuite:    test
           - compiler:     clang