diff --git a/meson.build b/meson.build
index 7241f537..5f965b19 100644
--- a/meson.build
+++ b/meson.build
@@ -42,6 +42,8 @@ compiler_options = [
   # Disable the use of concepts in Boost.Asio until Boost 1.73 gets released
   # https://github.com/boostorg/asio/issues/312
   '-DBOOST_ASIO_DISABLE_CONCEPTS',
+  # Boost.Process's auto detection for vfork() support doesn't seem to work
+  '-DBOOST_POSIX_HAS_VFORK=1',
   # We use an intrinsic to force flush-to-zero. SSE2 is always enabled in x86_64
   # CPUs, but when we're compiling the 32-bit bitbridge we need to manually add
   # this flag.
diff --git a/src/plugin/utils.cpp b/src/plugin/utils.cpp
index af6a0674..34f6c33c 100644
--- a/src/plugin/utils.cpp
+++ b/src/plugin/utils.cpp
@@ -16,9 +16,6 @@
 
 #include "utils.h"
 
-// Boost.Process's auto detection for vfork() support doesn't seem to work
-#define BOOST_POSIX_HAS_VFORK 1
-
 #include <unistd.h>
 #include <boost/dll/runtime_symbol_info.hpp>
 #include <boost/process/io.hpp>