diff --git a/lib/access.h b/lib/access.h
index 4273f06..0d2fc92 100644
--- a/lib/access.h
+++ b/lib/access.h
@@ -22,6 +22,11 @@
 #ifndef LIB_SENSORS_ACCESS_H
 #define LIB_SENSORS_ACCESS_H
 
+/* PATH_MAX is undefined on GNU Hurd */
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
 #include "sensors.h"
 #include "data.h"