diff --git a/ChangeLog b/ChangeLog
index 614658413..520e4b212 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,6 @@
 20000926
  - (djm) Update X11-askpass to 1.0.2 in RPM spec file
+ - (djm) Define _REENTRANT
 
 20000924
  - (djm) Merged cleanup patch from Mark Miller <markm@swoon.net>
diff --git a/defines.h b/defines.h
index 837ed0207..a8e2659c1 100644
--- a/defines.h
+++ b/defines.h
@@ -1,6 +1,11 @@
 #ifndef _DEFINES_H
 #define _DEFINES_H
 
+/* Some platforms need this for the _r() functions */
+#ifndef _REENTRANT
+# define _REENTRANT 1
+#endif
+
 /* Necessary headers */
 
 #include <sys/types.h> /* For [u]intxx_t */