diff --git a/core/net/ipv4/uip.c b/core/net/ipv4/uip.c
index f1bb7257a..174b0a3fa 100644
--- a/core/net/ipv4/uip.c
+++ b/core/net/ipv4/uip.c
@@ -699,7 +699,7 @@ uip_process(uint8_t flag)
     }
     goto drop;
 
-    /* Check if we were invoked because of the perodic timer fireing. */
+    /* Check if we were invoked because of the periodic timer firing. */
   } else if(flag == UIP_TIMER) {
 #if UIP_REASSEMBLY
     if(uip_reasstmr != 0) {
@@ -851,7 +851,7 @@ uip_process(uint8_t flag)
      that the packet has been corrupted in transit. If the size of
      uip_len is larger than the size reported in the IP packet header,
      the packet has been padded and we set uip_len to the correct
-     value.. */
+     value. */
 
   if((BUF->len[0] << 8) + BUF->len[1] <= uip_len) {
     uip_len = (BUF->len[0] << 8) + BUF->len[1];
@@ -891,7 +891,7 @@ uip_process(uint8_t flag)
 
   if(uip_ipaddr_cmp(&uip_hostaddr, &uip_all_zeroes_addr)) {
     /* If we are configured to use ping IP address configuration and
-       hasn't been assigned an IP address yet, we accept all ICMP
+       haven't been assigned an IP address yet, we accept all ICMP
        packets. */
 #if UIP_PINGADDRCONF && !NETSTACK_CONF_WITH_IPV6
     if(BUF->proto == UIP_PROTO_ICMP) {
@@ -1252,7 +1252,7 @@ uip_process(uint8_t flag)
     }
   }
 
-  /* If we didn't find and active connection that expected the packet,
+  /* If we didn't find an active connection that expected the packet,
      either this packet is an old duplicate, or this is a SYN packet
      destined for a connection in LISTEN. If the SYN flag isn't set,
      it is an old packet and we send a RST. */
@@ -1441,7 +1441,7 @@ uip_process(uint8_t flag)
   uip_flags = 0;
   /* We do a very naive form of TCP reset processing; we just accept
      any RST and kill our connection. We should in fact check if the
-     sequence number of this reset is wihtin our advertised window
+     sequence number of this reset is within our advertised window
      before we accept the reset. */
   if(BUF->flags & TCP_RST) {
     uip_connr->tcpstateflags = UIP_CLOSED;
diff --git a/core/net/rpl/rpl.c b/core/net/rpl/rpl.c
index f71c5fb4c..f92d5f5f8 100644
--- a/core/net/rpl/rpl.c
+++ b/core/net/rpl/rpl.c
@@ -76,9 +76,9 @@ rpl_set_mode(enum rpl_mode m)
      switching to. */
   if(m == RPL_MODE_MESH) {
 
-    /* If we switcht to mesh mode, we should send out a DAO message to
+    /* If we switch to mesh mode, we should send out a DAO message to
        inform our parent that we now are reachable. Before we do this,
-       we must set the mode variable, since DAOs will not be send if
+       we must set the mode variable, since DAOs will not be sent if
        we are in feather mode. */
     PRINTF("RPL: switching to mesh mode\n");
     mode = m;