Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -512,6 +512,8 @@ check_include_file( "fenv.h" HAVE_FENV_H )
 check_include_file( "inttypes.h" HAVE_INTTYPES_H )
 if( CMAKE_SYSTEM_NAME MATCHES "FreeBSD" )
   check_include_file( "stdlib.h" HAVE_MALLOC_H )
+elseif( CMAKE_SYSTEM_NAME MATCHES "OpenBSD" )
+  check_include_file( "stdlib.h" HAVE_MALLOC_H )
 else()
   check_include_file( "malloc.h" HAVE_MALLOC_H )
 endif()