diff --git a/.ci/azp-linux-test.yml b/.ci/azp-linux-test.yml
index 0520ea732..a49f3afcc 100644
--- a/.ci/azp-linux-test.yml
+++ b/.ci/azp-linux-test.yml
@@ -8,7 +8,7 @@ steps:
     set -e
     cd src/engine
     set PATH=${PATH};${CXX_PATH}
-    ./build.sh ${TOOLSET}
+    ./build.sh ${TOOLSET} --cxx=${CXX}
     ./b2 -v
     cd ../..
   displayName: Build
diff --git a/.ci/azp-macos-test.yml b/.ci/azp-macos-test.yml
index 2bc040e57..2841b83e0 100644
--- a/.ci/azp-macos-test.yml
+++ b/.ci/azp-macos-test.yml
@@ -8,7 +8,7 @@ steps:
 - bash: |
     set -e
     cd src/engine
-    ./build.sh ${TOOLSET}
+    ./build.sh ${TOOLSET} --cxx=${CXX}
     ./b2 -v
     cd ../..
   displayName: Build