diff --git a/cxx/filesystem.cpp b/cxx/filesystem.cpp
index a02cfbb..d821173 100644
--- a/cxx/filesystem.cpp
+++ b/cxx/filesystem.cpp
@@ -7,6 +7,11 @@
 #include <cstdio>
 #include <unistd.h>
 #include <sys/param.h>
+#include <limits.h>
+
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
 
 namespace filesystem {