diff --git a/setup_once.h b/setup_once.h
index fc630ef27..bb261e7a8 100644
--- a/setup_once.h
+++ b/setup_once.h
@@ -299,6 +299,18 @@ 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.