diff --git a/src/Config.c b/src/Config.c
index 50aff21..5a96a40 100644
--- a/src/Config.c
+++ b/src/Config.c
@@ -37,6 +37,10 @@
 #include <string.h>
 #include <limits.h>
 
+#ifndef HOST_NAME_MAX
+#define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
+#endif
+
 #define CONFIG_REQUIRE(key, type) \
     value = HashMapGet(config, key); \
     if (!value) \