diff --git a/submodules/build/iphone-config.site b/submodules/build/iphone-config.site
index a81401077..ee81ad99b 100644
--- a/submodules/build/iphone-config.site
+++ b/submodules/build/iphone-config.site
@@ -45,7 +45,7 @@ echo "Selecting SDK path = ${SYSROOT_PATH}"
 COMMON_FLAGS=" -arch ${ARCH} ${MCPU} -isysroot ${SYSROOT_PATH} -${CLANG_TARGET_SPECIFIER}=${SDK_VERSION} -DTARGET_OS_IPHONE=1 -D__IOS -fms-extensions"
 
 # silence clang unused operators. This is temporary, we should find a way to compile 3rd party with correct flags :(
-COMMON_FLAGS="-Qunused-arguments -Wno-unused-command-line-argument-hard-error-in-future $COMMON_FLAGS"
+COMMON_FLAGS="-Qunused-arguments -Wno-unknown-warning-option -Wno-unused-command-line-argument-hard-error-in-future $COMMON_FLAGS"
 
 CC="xcrun clang -std=c99 $COMMON_FLAGS"
 OBJC="xcrun clang -std=c99 $COMMON_FLAGS"