--- a/src/readline.c
+++ b/src/readline.c
@@ -59,6 +59,10 @@
 # define SIZE_T_MAX (size_t)(-1)
 #endif
 
+#if !defined(PATH_MAX)
+# define PATH_MAX 4096
+#endif
+
 void rl_prep_terminal(int);
 void rl_deprep_terminal(void);