diff --git a/src/core/tcp_in.c b/src/core/tcp_in.c
index abc6465..905f7cf 100644
--- a/src/core/tcp_in.c
+++ b/src/core/tcp_in.c
@@ -2029,7 +2029,7 @@ tcp_receive(struct tcp_pcb *pcb)
 #endif /* TCP_OOSEQ_BYTES_LIMIT || TCP_OOSEQ_PBUFS_LIMIT */
 #endif /* TCP_QUEUE_OOSEQ */
 
-#if GAZELLE_TCP_PINGONG_MODE
+#if GAZELLE_TCP_PINGPONG_MODE
         tcp_exit_pingpong(pcb); /* ooseq */
 #endif
         /* We send the ACK packet after we've (potentially) dealt with SACKs,
@@ -2038,7 +2038,7 @@ tcp_receive(struct tcp_pcb *pcb)
         tcp_send_empty_ack(pcb);
       }
     } else {
-#if GAZELLE_TCP_PINGONG_MODE
+#if GAZELLE_TCP_PINGPONG_MODE
       tcp_exit_pingpong(pcb); /* out of window */
 #endif
       /* The incoming segment is not within the window. */
