diff --git a/cmake/FindSSE.cmake b/cmake/FindSSE.cmake
index e8dc243d9b..0df9884a3d 100644
--- a/cmake/FindSSE.cmake
+++ b/cmake/FindSSE.cmake
@@ -2,6 +2,7 @@
 # SSE version (SSE 2.0, SSSE 3.0).
 
 include(CheckCXXSourceCompiles)
+set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
 set(CMAKE_REQUIRED_FLAGS "")
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang" OR CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
@@ -15,3 +16,5 @@ check_cxx_source_compiles("
     int main() { return 0; }"
     SSE_FOUND
 )
+
+set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
diff --git a/cmake/FindXaudio2.cmake b/cmake/FindXaudio2.cmake
index 477dfea728..777dd7ca2a 100644
--- a/cmake/FindXaudio2.cmake
+++ b/cmake/FindXaudio2.cmake
@@ -1,6 +1,7 @@
 # Autodetect if xaudio2 can be used.
 
 include(CheckCXXSourceCompiles)
+set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
 set(CMAKE_REQUIRED_FLAGS "")
 
 check_cxx_source_compiles("
@@ -17,3 +18,5 @@ check_cxx_source_compiles("
     int main() { printf(\"%s\\\\n\", XAUDIO2_DLL_A); return 0; }"
     XAUDIO2_FOUND
 )
+
+set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
diff --git a/os/emscripten/cmake/FindLibLZMA.cmake b/os/emscripten/cmake/FindLibLZMA.cmake
index 0880d62f70..47fab8c9d0 100644
--- a/os/emscripten/cmake/FindLibLZMA.cmake
+++ b/os/emscripten/cmake/FindLibLZMA.cmake
@@ -1,6 +1,7 @@
 # LibLZMA is a custom addition to the emscripten SDK, so it is possible
 # someone patched their SDK. Test out if the SDK supports LibLZMA.
 include(CheckCXXSourceCompiles)
+set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
 set(CMAKE_REQUIRED_FLAGS "--use-port=contrib.liblzma")
 
 check_cxx_source_compiles("
@@ -18,3 +19,5 @@ if (LIBLZMA_FOUND)
 else()
         message(WARNING "You are using an emscripten SDK without LibLZMA support. Many savegames won't be able to load in OpenTTD. Please copy liblzma.py to your ports/contrib folder in your local emsdk installation.")
 endif()
+
+set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})