diff --git a/include/ac/param.h b/include/ac/param.h
index 4130f6ebe5446de6c63fb07eebffb05003c5b304..b3eb5d7c31e464a4777c54038f340972ac83a624 100644
--- a/include/ac/param.h
+++ b/include/ac/param.h
@@ -21,6 +21,9 @@
 #include <sys/param.h>
 #endif
 
+/* MAXPATHLEN should come from <unistd.h> */
+#include <ac/unistd.h>
+
 #ifndef MAXPATHLEN
 #	if defined(PATH_MAX)
 #		define MAXPATHLEN	PATH_MAX