--- a/cmake/CheckIncludeFiles.cmake
+++ b/cmake/CheckIncludeFiles.cmake
@@ -50,4 +50,11 @@
 CHECK_INCLUDE_FILES (ucontext.h HAVE_FILE_UCONTEXT_H)
 IF(NOT HAVE_FILE_UCONTEXT_H)
   CHECK_INCLUDE_FILES (sys/ucontext.h HAVE_FILE_UCONTEXT_H)
+  CHECK_FUNCTION_EXISTS (getcontext HAVE_GETCONTEXT)
+  CHECK_FUNCTION_EXISTS (makecontext HAVE_MAKECONTEXT)
+  CHECK_FUNCTION_EXISTS (setcontext HAVE_SETCONTEXT)
+  CHECK_FUNCTION_EXISTS (swapcontext HAVE_SWAPCONTEXT)
+  IF(NOT HAVE_GETCONTEXT OR NOT HAVE_MAKECONTEXT OR NOT HAVE_SETCONTEXT OR NOT HAVE_SWAPCONTEXT)
+    SET(HAVE_UCONTEXT_H 0 CACHE INTERNAL "")
+  ENDIF()
 ENDIF()
--- a/cmake/CheckTypes.cmake
+++ b/cmake/CheckTypes.cmake
@@ -21,7 +21,6 @@
 CHECK_TYPE_SIZE(size_t SIZEOF_SIZE_T)
 SET(CMAKE_EXTRA_INCLUDE_FILES sys/types.h)
 CHECK_TYPE_SIZE(uint SIZEOF_UINT)
-CHECK_TYPE_SIZE(uint SIZEOF_USHORT)
 CHECK_TYPE_SIZE(ulong SIZEOF_ULONG)
 CHECK_TYPE_SIZE(int8 SIZEOF_INT8)
 CHECK_TYPE_SIZE(uint8 SIZEOF_UINT8)