#endif
#ifndef VMG_MULTIPLICITY
-# if defined(MULTIPLICITY) || defined(PERL_IMPLICIT_CONTEXT)
+# if defined(MULTIPLICITY)
# define VMG_MULTIPLICITY 1
# else
# define VMG_MULTIPLICITY 0
# endif
#endif
+#if VMG_MULTIPLICITY
+# ifndef PERL_IMPLICIT_CONTEXT
+# error MULTIPLICITY builds must set PERL_IMPLICIT_CONTEXT
+# endif
+#endif
#if VMG_MULTIPLICITY && defined(USE_ITHREADS) && defined(dMY_CXT) && defined(MY_CXT) && defined(START_MY_CXT) && defined(MY_CXT_INIT) && (defined(MY_CXT_CLONE) || defined(dMY_CXT_SV))
# define VMG_THREADSAFE 1