diff --git a/cmake/shared_prologue.cmake b/cmake/shared_prologue.cmake
index 5c46c9cf..2265af77 100644
--- a/cmake/shared_prologue.cmake
+++ b/cmake/shared_prologue.cmake
@@ -94,6 +94,17 @@ add_library(clap-wrapper-compile-options INTERFACE)
 add_library(clap-wrapper-compile-options-public INTERFACE)
 target_link_libraries(clap-wrapper-compile-options INTERFACE clap-wrapper-compile-options-public)
 
+# The wrapper sources need C++17 - std::filesystem, if-initializers - and carry that requirement
+# themselves rather than leaving it to whoever is building them. The top-level CMakeLists sets
+# CMAKE_CXX_STANDARD, but only when it *is* the top level, so a project that reaches the wrapper
+# through add_subdirectory got no floor at all and failed in clap_proxy.cpp and
+# preset_discovery.cpp against a generator default older than 17 - Xcode's, for one, which is how
+# this surfaced while following docs/ios.md.
+#
+# A floor, not a pin: a consumer building at 20 stays at 20. It only raises a build that was
+# below 17, which was never a configuration this project supported.
+target_compile_features(clap-wrapper-compile-options-public INTERFACE cxx_std_17)
+
 # This is useful for debugging cmake link problems2
 # target_compile_definitions(clap-wrapper-compile-options INTERFACE -DTHIS_BUILD_USED_CLAP_WRAPPER_COMPILE_OPTIONS=1)
 # target_compile_definitions(clap-wrapper-compile-options-public INTERFACE -DTHIS_BUILD_USED_CLAP_WRAPPER_COMPILE_OPTIONS_PUBLIC=1)
diff --git a/docs/ios.md b/docs/ios.md
index 733ae39e..4bad4c8f 100644
--- a/docs/ios.md
+++ b/docs/ios.md
@@ -254,6 +254,7 @@ still installed and still works normally in external hosts.
 | Host shows "Factory class ... is not linked" | Host target missing the entry source / impl library, or AU codes differ between host and appex |
 | Plugin appears on iPhone but not on iPad | Device family mismatch; both bundles must be `1,2` |
 | GUI stays empty | Plugin does not implement the `CLAP_WINDOW_API_UIKIT` window API |
+| Errors in `clap_proxy.cpp` or `preset_discovery.cpp` about `std::filesystem` or `if` initializers | The project is building below C++17. The wrapper now carries a `cxx_std_17` floor, so this only appears against older wrapper versions; set `CMAKE_CXX_STANDARD` to 17 or higher in your own project |
 
 ## Current limitations