diff --git a/include/ZeroTierOne.h b/include/ZeroTierOne.h
index e6ec80909..2a970d5b8 100644
--- a/include/ZeroTierOne.h
+++ b/include/ZeroTierOne.h
@@ -92,6 +92,21 @@ extern "C" {
  */
 #define ZT_MAX_MTU 10000
 
+/**
+ * Maximum physical UDP payload
+ */
+#define ZT_MAX_PHYSPAYLOAD 10100
+
+/**
+ * Headroom for max physical MTU
+ */
+#define ZT_MAX_HEADROOM 224
+
+/**
+ * Maximum physical MTU
+ */
+#define ZT_MAX_PHYSMTU (ZT_MAX_PHYSPAYLOAD + ZT_MAX_HEADROOM)
+
 /**
  * Maximum size of a remote trace message's serialized Dictionary
  */