diff --git a/mongoose.h b/mongoose.h
index e6a5ce6e..359e5261 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -580,7 +580,9 @@ int sscanf(const char *, const char *, ...);
 
 #define sockaddr_in freertos_sockaddr
 #define sockaddr freertos_sockaddr
+#if ipFR_TCP_VERSION_MAJOR >= 4
 #define sin_addr sin_address.ulIP_IPv4
+#endif
 #define accept(a, b, c) FreeRTOS_accept((a), (b), (c))
 #define connect(a, b, c) FreeRTOS_connect((a), (b), (c))
 #define bind(a, b, c) FreeRTOS_bind((a), (b), (c))
diff --git a/src/net_ft.h b/src/net_ft.h
index d00c3b9a..8d0767b2 100644
--- a/src/net_ft.h
+++ b/src/net_ft.h
@@ -38,7 +38,9 @@
 
 #define sockaddr_in freertos_sockaddr
 #define sockaddr freertos_sockaddr
+#if ipFR_TCP_VERSION_MAJOR >= 4
 #define sin_addr sin_address.ulIP_IPv4
+#endif
 #define accept(a, b, c) FreeRTOS_accept((a), (b), (c))
 #define connect(a, b, c) FreeRTOS_connect((a), (b), (c))
 #define bind(a, b, c) FreeRTOS_bind((a), (b), (c))