diff --git a/src/core/tcp_out.c b/src/core/tcp_out.c
index a64e420d..3c2bc81a 100644
--- a/src/core/tcp_out.c
+++ b/src/core/tcp_out.c
@@ -224,7 +224,7 @@ tcp_create_segment(struct tcp_pcb *pcb, struct pbuf *p, u8_t flags, u32_t seqno,
  * @param length size of the pbuf's payload.
  * @param max_length maximum usable size of payload+oversize.
  * @param oversize pointer to a u16_t that will receive the number of usable tail bytes.
- * @param pcb The TCP connection that willo enqueue the pbuf.
+ * @param pcb The TCP connection that will enqueue the pbuf.
  * @param apiflags API flags given to tcp_write.
  * @param first_seg true when this pbuf will be used in the first enqueued segment.
  */