diff --git a/procname.c b/procname.c
index 262d63a4..e28b7535 100644
--- a/procname.c
+++ b/procname.c
@@ -25,7 +25,9 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifndef nitems
 #define nitems(_a) (sizeof((_a)) / sizeof((_a)[0]))
+#endif
 
 #define is_runnable(p) \
 	((p)->p_stat == SRUN || (p)->p_stat == SIDL || (p)->p_stat == SONPROC)