diff --git a/src/acconfig.h b/src/acconfig.h
index 940fa66156ef192730a847d767deaaa35f349fce..91d671adecc5d708f7b4d3c87fde50ff3c7e5fd8 100644
--- a/src/acconfig.h
+++ b/src/acconfig.h
@@ -1,5 +1,5 @@
 /*
- * $Id: acconfig.h,v 1.45 1999/07/15 16:54:33 hubbe Exp $
+ * $Id: acconfig.h,v 1.46 1999/08/10 00:18:58 mast Exp $
  */
 #ifndef MACHINE_H
 #define MACHINE_H
@@ -212,6 +212,7 @@
 #undef USHRT_MAX
 
 /* Define these if you are going to use threads */
+#undef PIKE_THREADS
 #undef _REENTRANT
 #undef _THREAD_SAFE
 
diff --git a/src/configure.in b/src/configure.in
index 93c0974a530aa8a96fca5a49b418bf20ed570191..c2d1b62297d456c700fbdc365e07cb363d86d8d1 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -1,4 +1,4 @@
-AC_REVISION("$Id: configure.in,v 1.304 1999/08/07 23:42:47 grubba Exp $")
+AC_REVISION("$Id: configure.in,v 1.305 1999/08/10 00:18:59 mast Exp $")
 AC_INIT(interpret.c)
 AC_CONFIG_HEADER(machine.h)
 
@@ -1162,6 +1162,7 @@ fi
 ########################################################################
 
 if test x$with_threads = xyes ; then
+  AC_DEFINE(PIKE_THREADS)
   OLDLIBS="$LIBS"
   OLDCFLAGS="$CFLAGS"
 
diff --git a/src/threads.h b/src/threads.h
index a6a641476c3adfad922e34bd467026a77bc127e6..20551ca68f6abfac839852f1cca479e9da99ce1d 100644
--- a/src/threads.h
+++ b/src/threads.h
@@ -1,5 +1,5 @@
 /*
- * $Id: threads.h,v 1.67 1999/05/12 04:45:59 hubbe Exp $
+ * $Id: threads.h,v 1.68 1999/08/10 00:19:00 mast Exp $
  */
 #ifndef THREADS_H
 #define THREADS_H
@@ -12,7 +12,7 @@
 /* Needed for pthread_t on OSF/1 */
 #include <sys/types.h>
 #endif /* HAVE_SYS_TYPES_H */
-#ifdef _REENTRANT
+#ifdef PIKE_THREADS
 
 /*
  * Decide which type of threads to use
@@ -603,7 +603,7 @@ void th_farm(void (*fun)(void *), void *here);
 #define init_threads_disable(X)
 #define exit_threads_disable(X)
 
-#endif /* _REENTRANT */
+#endif /* PIKE_THREADS */
 
 #ifdef __NT__
 #ifndef PIKE_DEBUG