diff --git a/lib/setup_once.h b/lib/setup_once.h
index eb14e5886..0bf49b72e 100644
--- a/lib/setup_once.h
+++ b/lib/setup_once.h
@@ -316,6 +316,18 @@ struct timeval {
 #endif
 
 
+/*
+ * Some HP-UX system headers require TRUE defined to 1 and FALSE to 0.
+ */
+
+#if defined(__hpux)
+#undef TRUE
+#define TRUE 1
+#undef FALSE
+#define FALSE 0
+#endif
+
+
 /*
  * Macro WHILE_FALSE may be used to build single-iteration do-while loops,
  * avoiding compiler warnings. Mostly intended for other macro definitions.