diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index bb2db529..3cbfb084 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -694,7 +694,7 @@ tcp_process(struct tcp_pcb *pcb)
       LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: Connection RESET\n"));
       LWIP_ASSERT("tcp_input: pcb->state != CLOSED", pcb->state != CLOSED);
       recv_flags |= TF_RESET;
-      pcb->flags &= (tcpflags_t)~(unsigned int)TF_ACK_DELAY;
+      pcb->flags &= ~TF_ACK_DELAY;
       return ERR_RST;
     } else {
       LWIP_DEBUGF(TCP_INPUT_DEBUG, ("tcp_process: unacceptable reset seqno %"U32_F" rcv_nxt %"U32_F"\n",
@@ -1062,7 +1062,7 @@ tcp_receive(struct tcp_pcb *pcb)
          in fast retransmit. Also reset the congestion window to the
          slow start threshold. */
       if (pcb->flags & TF_INFR) {
-        pcb->flags &= (tcpflags_t)~(unsigned int)TF_INFR;
+        pcb->flags &= ~TF_INFR;
         pcb->cwnd = pcb->ssthresh;
       }
 
@@ -1338,7 +1338,7 @@ tcp_receive(struct tcp_pcb *pcb)
           if (TCPH_FLAGS(inseg.tcphdr) & TCP_FIN) {
             /* Must remove the FIN from the header as we're trimming 
              * that byte of sequence-space from the packet */
-            TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) & (tcpflags_t)~(unsigned int)TCP_FIN);
+            TCPH_FLAGS_SET(inseg.tcphdr, TCPH_FLAGS(inseg.tcphdr) & ~(unsigned int)TCP_FIN);
           }
           /* Adjust length of segment to fit in the window. */
           inseg.len = pcb->rcv_wnd;
@@ -1593,7 +1593,7 @@ tcp_receive(struct tcp_pcb *pcb)
                     if (TCPH_FLAGS(next->next->tcphdr) & TCP_FIN) {
                       /* Must remove the FIN from the header as we're trimming 
                        * that byte of sequence-space from the packet */
-                      TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) & (tcpflags_t)~(unsigned int)TCP_FIN);
+                      TCPH_FLAGS_SET(next->next->tcphdr, TCPH_FLAGS(next->next->tcphdr) & ~TCP_FIN);
                     }
                     /* Adjust length of segment to fit in the window. */
                     next->next->len = (u16_t)(pcb->rcv_nxt + pcb->rcv_wnd - seqno);
diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index 589ef5dd..ec42164b 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -1112,7 +1112,7 @@ tcp_output(struct tcp_pcb *pcb)
   }
 #endif /* TCP_OVERSIZE */
 
-  pcb->flags &= (tcpflags_t)~(unsigned int)TF_NAGLEMEMERR;
+  pcb->flags &= ~TF_NAGLEMEMERR;
   return ERR_OK;
 }
 
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index 69c39de1..a9099d51 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -189,16 +189,16 @@ struct tcp_pcb {
   u16_t remote_port;
   
   tcpflags_t flags;
-#define TF_ACK_DELAY   ((tcpflags_t)0x0001U)   /* Delayed ACK. */
-#define TF_ACK_NOW     ((tcpflags_t)0x0002U)   /* Immediate ACK. */
-#define TF_INFR        ((tcpflags_t)0x0004U)   /* In fast recovery. */
-#define TF_TIMESTAMP   ((tcpflags_t)0x0008U)   /* Timestamp option enabled */
-#define TF_RXCLOSED    ((tcpflags_t)0x0010U)   /* rx closed by tcp_shutdown */
-#define TF_FIN         ((tcpflags_t)0x0020U)   /* Connection was closed locally (FIN segment enqueued). */
-#define TF_NODELAY     ((tcpflags_t)0x0040U)   /* Disable Nagle algorithm */
-#define TF_NAGLEMEMERR ((tcpflags_t)0x0080U)   /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
+#define TF_ACK_DELAY   0x01U   /* Delayed ACK. */
+#define TF_ACK_NOW     0x02U   /* Immediate ACK. */
+#define TF_INFR        0x04U   /* In fast recovery. */
+#define TF_TIMESTAMP   0x08U   /* Timestamp option enabled */
+#define TF_RXCLOSED    0x10U   /* rx closed by tcp_shutdown */
+#define TF_FIN         0x20U   /* Connection was closed locally (FIN segment enqueued). */
+#define TF_NODELAY     0x40U   /* Disable Nagle algorithm */
+#define TF_NAGLEMEMERR 0x80U   /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
 #if LWIP_WND_SCALE
-#define TF_WND_SCALE   ((tcpflags_t)0x0100U)   /* Window Scale option enabled */
+#define TF_WND_SCALE   0x0100U /* Window Scale option enabled */
 #endif
 
   /* the rest of the fields are in host byte order
@@ -351,7 +351,7 @@ void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
 #define          tcp_sndbuf(pcb)          ((pcb)->snd_buf)
 #define          tcp_sndqueuelen(pcb)     ((pcb)->snd_queuelen)
 #define          tcp_nagle_disable(pcb)   ((pcb)->flags |= TF_NODELAY)
-#define          tcp_nagle_enable(pcb)    ((pcb)->flags &= (tcpflags_t)~(unsigned int)TF_NODELAY)
+#define          tcp_nagle_enable(pcb)    ((pcb)->flags &= ~TF_NODELAY)
 #define          tcp_nagle_disabled(pcb)  (((pcb)->flags & TF_NODELAY) != 0)
 
 #if TCP_LISTEN_BACKLOG
diff --git a/src/include/lwip/tcp_impl.h b/src/include/lwip/tcp_impl.h
index 1ddfcadb..b02b054c 100644
--- a/src/include/lwip/tcp_impl.h
+++ b/src/include/lwip/tcp_impl.h
@@ -182,7 +182,7 @@ PACK_STRUCT_END
 #define TCPH_FLAGS(phdr)  (ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS)
 
 #define TCPH_HDRLEN_SET(phdr, len) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | TCPH_FLAGS(phdr))
-#define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS((u16_t)(~(unsigned int)(TCP_FLAGS)))) | htons(flags))
+#define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS(~TCP_FLAGS)) | htons(flags))
 #define TCPH_HDRLEN_FLAGS_SET(phdr, len, flags) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | (flags))
 
 #define TCPH_SET_FLAG(phdr, flags ) (phdr)->_hdrlen_rsvd_flags = ((phdr)->_hdrlen_rsvd_flags | htons(flags))
@@ -460,7 +460,7 @@ struct tcp_seg *tcp_seg_copy(struct tcp_seg *seg);
 #define tcp_ack(pcb)                               \
   do {                                             \
     if((pcb)->flags & TF_ACK_DELAY) {              \
-      (pcb)->flags &= (tcpflags_t)~(unsigned int)TF_ACK_DELAY; \
+      (pcb)->flags &= ~TF_ACK_DELAY;               \
       (pcb)->flags |= TF_ACK_NOW;                  \
     }                                              \
     else {                                         \