diff --git a/.github/workflows/matrix_build.yml b/.github/workflows/matrix_build.yml
index 21a9b1f1..af393689 100644
--- a/.github/workflows/matrix_build.yml
+++ b/.github/workflows/matrix_build.yml
@@ -350,6 +350,7 @@ jobs:
           echo "BR2_TOOLCHAIN_EXTERNAL=y" >> $CONF_PATH
           echo "BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y" >> $CONF_PATH
           echo "BR2_TOOLCHAIN_EXTERNAL_PREINSTALLED=y" >> $CONF_PATH
+          echo "BR2_TOOLCHAIN_EXTERNAL_CXX=y" >> $CONF_PATH
           echo "BR2_TOOLCHAIN_EXTERNAL_PATH=\"/tmp/extsdk\"" >> $CONF_PATH
 
           SOC=$(echo $TOOLNAME | cut -d '-' -f 1)