diff --git a/pqsort.c b/pqsort.c
index 8e2b12483..59dedcbc3 100644
--- a/pqsort.c
+++ b/pqsort.c
@@ -37,7 +37,9 @@
  * SUCH DAMAGE.
  */
 
+#ifndef __P
 #define __P(protos) protos
+#endif
 
 #include <sys/cdefs.h>
 #if defined(LIBC_SCCS) && !defined(lint)