diff --git a/src/core/init.c b/src/core/init.c
index 5e19a98a..1f658676 100644
--- a/src/core/init.c
+++ b/src/core/init.c
@@ -305,6 +305,9 @@ PACK_STRUCT_END
 #if TCP_SNDLOWAT >= TCP_SND_BUF
 #error "lwip_sanity_check: WARNING: TCP_SNDLOWAT must be less than TCP_SND_BUF. If you know what you are doing, define LWIP_DISABLE_TCP_SANITY_CHECKS to 1 to disable this error."
 #endif
+#if TCP_MSS >= ((16 * 1024) - 1)
+#error "lwip_sanity_check: WARNING: TCP_MSS must be <= 16382 to prevent u16_t underflow in TCP_SNDLOWAT calculation!"
+#endif
 #if TCP_SNDLOWAT >= (0xFFFF - (4 * TCP_MSS))
 #error "lwip_sanity_check: WARNING: TCP_SNDLOWAT must at least be 4*MSS below u16_t overflow!"
 #endif