diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a075d54..d947617 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,6 +21,7 @@ jobs:
 
           - lib: filesystem
             bopts: install
+            copts: -DCMAKE_CXX_STANDARD=11
             os: macos-latest
 
           # --layout=versioned
@@ -31,6 +32,7 @@ jobs:
 
           - lib: filesystem
             bopts: --layout=versioned install
+            copts: -DCMAKE_CXX_STANDARD=11
             os: macos-latest
 
           # --layout=tagged
@@ -41,6 +43,7 @@ jobs:
 
           - lib: filesystem
             bopts: --layout=tagged install
+            copts: -DCMAKE_CXX_STANDARD=11
             os: macos-latest
 
           # build with clang++, use with g++
@@ -163,7 +166,7 @@ jobs:
 
           - lib: filesystem
             bopts: stage
-            copts: -DUSE_STAGED_BOOST=ON
+            copts: -DUSE_STAGED_BOOST=ON -DCMAKE_CXX_STANDARD=11
             os: macos-latest
 
           - lib: filesystem