diff --git a/cmake/osx_i686.toolchain.cmake b/cmake/osx_i686.toolchain.cmake
new file mode 100644
index 000000000..ada155532
--- /dev/null
+++ b/cmake/osx_i686.toolchain.cmake
@@ -0,0 +1,11 @@
+# toolchain file for building a 32bit version on a 64bit host
+
+# use it like this:
+# cmake -DCMAKE_TOOLCHAIN_FILE=osx.toolchain.cmake <sourcedir>
+
+set(CMAKE_SYSTEM_NAME OSX)
+set(CMAKE_SYSTEM_VERSION 1)
+set(CMAKE_SYSTEM_PROCESSOR "i686")
+
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32" CACHE STRING "c++ flags")
+set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS} -m32" CACHE STRING "c flags")