diff --git a/cmake-utils/conan-setup.cmake b/cmake-utils/conan-setup.cmake
index 84999547..4147320e 100644
--- a/cmake-utils/conan-setup.cmake
+++ b/cmake-utils/conan-setup.cmake
@@ -6,14 +6,20 @@ macro(setup_conan)
             CONANFILE conanfile.py
             BUILD missing)
     else()
+        # We're using set(_GLIBCXX_USE_CXX11_ABI 1), because conan_cmake_run looks at that variable
+        # to set conan to libstdc++11 instead of libstdc++. This would also work by passing in
+        # a "SETTINGS compiler.libcxx=libstdc++11" to conan_cmake_run, but for some reason the logs
+        # then show that conan ran with both "-s compiler.libcxx=libstdc++ -s compiler.libcxx=libstdc++11"
+        # which seems wrong. Using the set() approach instead, that command line only has the correct
+        # "-s compiler.libcxx=libstdc++11".
+        # See https://github.com/conan-io/cmake-conan/issues/255
+        # We're using set() instead of add_definitions() because of https://github.com/conan-io/cmake-conan/issues/256
+        set(_GLIBCXX_USE_CXX11_ABI 1)
         conan_cmake_run(
             CONANFILE conanfile.py
             # We'd like to use "BUILD missing" but that doesn't work because conan sometimes seems to download prebuilt packages with compiler.libcxx=libstdc++ even though we specify compiler.libcxx=libstdc++11.
             # see https://github.com/cryfs/cryfs/issues/336 and https://github.com/conan-io/conan/issues/7264
-            BUILD all
-            # Note: This way of passing compiler.libcxx seems to work, but there's an issue. See https://github.com/conan-io/cmake-conan/issues/255
-            # see also as a related issue: https://github.com/conan-io/cmake-conan/issues/256
-            SETTINGS compiler.libcxx=libstdc++11)
+            BUILD all)
     endif()
     conan_basic_setup(TARGETS SKIP_STD)