diff --git a/reactos/dll/3rdparty/libxslt/CMakeLists.txt b/reactos/dll/3rdparty/libxslt/CMakeLists.txt
index e90c979763c..cf5789fdc2b 100644
--- a/reactos/dll/3rdparty/libxslt/CMakeLists.txt
+++ b/reactos/dll/3rdparty/libxslt/CMakeLists.txt
@@ -46,5 +46,6 @@ add_pch(libxslt libxslt.h)
 add_cd_file(TARGET libxslt DESTINATION reactos/system32 FOR all)
 
 if(NOT MSVC)
+    add_target_compile_flags(libxslt "-Wno-pointer-sign")
     allow_warnings(libxslt)
 endif()
diff --git a/reactos/lib/3rdparty/libxml2/CMakeLists.txt b/reactos/lib/3rdparty/libxml2/CMakeLists.txt
index 8d18f18d0f9..3da4e5b0b05 100644
--- a/reactos/lib/3rdparty/libxml2/CMakeLists.txt
+++ b/reactos/lib/3rdparty/libxml2/CMakeLists.txt
@@ -61,5 +61,6 @@ target_link_libraries(libxml2 oldnames)
 add_dependencies(libxml2 psdk)
 
 if(NOT MSVC)
+    add_target_compile_flags(libxml2 "-Wno-format -Wno-pointer-sign")
     allow_warnings(libxml2)
 endif()