diff --git a/src/include/lwip/priv/tcp_priv.h b/src/include/lwip/priv/tcp_priv.h
index afd6f937..c0c9110d 100644
--- a/src/include/lwip/priv/tcp_priv.h
+++ b/src/include/lwip/priv/tcp_priv.h
@@ -112,16 +112,6 @@ err_t            tcp_process_refused_data(struct tcp_pcb *pcb);
 #define TCP_SEQ_BETWEEN(a,b,c) ((c)-(b) >= (a)-(b))
 #endif
 #define TCP_SEQ_BETWEEN(a,b,c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))
-#define TCP_FIN 0x01U
-#define TCP_SYN 0x02U
-#define TCP_RST 0x04U
-#define TCP_PSH 0x08U
-#define TCP_ACK 0x10U
-#define TCP_URG 0x20U
-#define TCP_ECE 0x40U
-#define TCP_CWR 0x80U
-
-#define TCP_FLAGS 0x3fU
 
 #ifndef TCP_TMR_INTERVAL
 #define TCP_TMR_INTERVAL       250  /* The TCP timer interval in milliseconds. */
diff --git a/src/include/lwip/prot/tcp.h b/src/include/lwip/prot/tcp.h
index 3e263304..8ef0bf1d 100644
--- a/src/include/lwip/prot/tcp.h
+++ b/src/include/lwip/prot/tcp.h
@@ -68,6 +68,18 @@ PACK_STRUCT_END
 #  include "arch/epstruct.h"
 #endif
 
+/* TCP header flags bits */
+#define TCP_FIN 0x01U
+#define TCP_SYN 0x02U
+#define TCP_RST 0x04U
+#define TCP_PSH 0x08U
+#define TCP_ACK 0x10U
+#define TCP_URG 0x20U
+#define TCP_ECE 0x40U
+#define TCP_CWR 0x80U
+/* Valid TCP header flags */
+#define TCP_FLAGS 0x3fU
+
 #define TCPH_HDRLEN(phdr) ((u16_t)(ntohs((phdr)->_hdrlen_rsvd_flags) >> 12))
 #define TCPH_FLAGS(phdr)  ((u16_t)(ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS))