diff --git a/idle_scan.cc b/idle_scan.cc
index a7bad3a07..1d54fd5c3 100644
--- a/idle_scan.cc
+++ b/idle_scan.cc
@@ -260,7 +260,7 @@ static void initialize_proxy_struct(struct idle_proxy_info *proxy) {
   proxy->ethptr = NULL;
 }
 
-/* takes a proxy name/IP, resolves it if neccessary, tests it for IP ID
+/* takes a proxy name/IP, resolves it if necessary, tests it for IP ID
    suitability, and fills out an idle_proxy_info structure.  If the
    proxy is determined to be unsuitable, the function whines and exits
    the program */
diff --git a/nmap.h b/nmap.h
index efed8551a..6f479c7ec 100644
--- a/nmap.h
+++ b/nmap.h
@@ -431,7 +431,7 @@ void free_scan_lists(struct scan_lists *ports);
 /* socket manipulation functions */
 void init_socket(int sd);
 
-/* Renamed main so that interactive mode could preprocess when neccessary */
+/* Renamed main so that interactive mode could preprocess when necessary */
 int nmap_main(int argc, char *argv[]);
 
 void nmap_free_mem();
diff --git a/portlist.cc b/portlist.cc
index 4907bc6bd..05ec7dfa7 100644
--- a/portlist.cc
+++ b/portlist.cc
@@ -293,7 +293,7 @@ const void PortList::getServiceDeductions(u16 portno, int protocol, struct servi
 // will be NULL if unavailable. Note that this function makes its
 // own copy of sname and product/version/extrainfo.  This function
 // also takes care of truncating the version strings to a
-// 'reasonable' length if neccessary, and cleaning up any unprintable
+// 'reasonable' length if necessary, and cleaning up any unprintable
 // chars. (these tests are to avoid annoying DOS (or other) attacks
 // by malicious services).  The fingerprint should be NULL unless
 // one is available and the user should submit it.  tunnel must be
diff --git a/portlist.h b/portlist.h
index 392d4426a..680ee614c 100644
--- a/portlist.h
+++ b/portlist.h
@@ -254,7 +254,7 @@ class PortList {
   // will be NULL if unavailable. Note that this function makes its
   // own copy of sname and product/version/extrainfo.  This function
   // also takes care of truncating the version strings to a
-  // 'reasonable' length if neccessary, and cleaning up any unprinable
+  // 'reasonable' length if necessary, and cleaning up any unprinable
   // chars. (these tests are to avoid annoying DOS (or other) attacks
   // by malicious services).  The fingerprint should be NULL unless
   // one is available and the user should submit it.  tunnel must be
diff --git a/scan_engine.cc b/scan_engine.cc
index 31056b30c..f1c181dff 100644
--- a/scan_engine.cc
+++ b/scan_engine.cc
@@ -127,7 +127,7 @@ struct ultra_scan_performance_vars {
 		       increments. */
   int initial_ssthresh;
   /* When a successful ping response comes back, it counts as this many
-     "normal" responses, because the fact that pings are neccessary means
+     "normal" responses, because the fact that pings are necessary means
      we aren't getting much input. */
   int ping_magnifier;
 /* Try to send a scanping if no response has been received from a target host
@@ -498,7 +498,7 @@ public:
   unsigned int num_probes_active;
   /* Probes timed out but not yet retransmitted because of congestion
      control limits or because more retransmits may not be
-     neccessary.  Note that probes on probe_bench are not included
+     necessary.  Note that probes on probe_bench are not included
      in this value. */
   unsigned int num_probes_waiting_retransmit;
   unsigned int num_probes_outstanding() { return probes_outstanding.size(); }
@@ -1341,7 +1341,7 @@ unsigned int HostScanStats::allowedTryno(bool *capped, bool *mayincrease) {
   /* Decide if the tryno can possibly increase.  */
   if (tryno_mayincrease && num_probes_active == 0 && freshPortsLeft() == 0) {
     /* If every outstanding probe is timedout and at maxval, then no further
-       retransmits are neccessary. */
+       retransmits are necessary. */
     for(probeI = probes_outstanding.begin(); 
 	probeI != probes_outstanding.end(); probeI++) {
       probe = *probeI;
@@ -2274,7 +2274,7 @@ static void ultrascan_adjust_timing(UltraScanInfo *USI, HostScanStats *hss,
     //    printf("SDELAY: increasing good to %d (bad: %d)\n", hss->sdn.goodRespSinceDelayChanged, hss->sdn.droppedRespSinceDelayChanged);
   }
 
-  /* Now change the send delay if neccessary */
+  /* Now change the send delay if necessary */
   unsigned int oldgood = hss->sdn.goodRespSinceDelayChanged;
   unsigned int oldbad = hss->sdn.droppedRespSinceDelayChanged;
   double threshold = (o.timing_level >= 4)? 0.40 : 0.30;
diff --git a/service_scan.cc b/service_scan.cc
index 90c335594..47cdfbe24 100644
--- a/service_scan.cc
+++ b/service_scan.cc
@@ -1695,7 +1695,7 @@ ServiceGroup::~ServiceGroup() {
 
 /* Called if data is read for a service or a TCP connection made. Sets the port
    state to PORT_OPEN. */
-static void adjustPortStateIfNeccessary(ServiceNFO *svc) {
+static void adjustPortStateIfNecessary(ServiceNFO *svc) {
   int oldstate;
   char host[128];
 
@@ -1744,7 +1744,7 @@ static void adjustPortStateIfNeccessary(ServiceNFO *svc) {
 
 // This simple helper function is used to start the next probe.  If
 // the probe exists, execution begins (and the previous one is cleaned
-// up if neccessary) .  Otherwise, the service is listed as finished
+// up if necessary) .  Otherwise, the service is listed as finished
 // and moved to the finished list.  If you pass 'true' for alwaysrestart, a
 // new connection will be made even if the previous probe was the NULL probe.
 // You would do this, for example, if the other side has closed the connection.
@@ -2045,7 +2045,7 @@ static void servicescan_connect_handler(nsock_pool nsp, nsock_event nse, void *m
 
     /* If the port is TCP, it is now known to be open rather than openfiltered */
     if (svc->proto == IPPROTO_TCP)
-      adjustPortStateIfNeccessary(svc);
+      adjustPortStateIfNecessary(svc);
 
     // Yeah!  Connection made to the port.  Send the appropriate probe
     // text (if any is needed -- might be NULL probe)
@@ -2142,7 +2142,7 @@ static void servicescan_read_handler(nsock_pool nsp, nsock_event nse, void *myda
   } else if (status == NSE_STATUS_SUCCESS) {
     // w00p, w00p, we read something back from the port.
     readstr = (u8 *) nse_readbuf(nse, &readstrlen);
-    adjustPortStateIfNeccessary(svc); /* A response means PORT_OPENFILTERED is really PORT_OPEN */
+    adjustPortStateIfNecessary(svc); /* A response means PORT_OPENFILTERED is really PORT_OPEN */
     svc->appendtocurrentproberesponse(readstr, readstrlen);
     // now get the full version
     readstr = svc->getcurrentproberesponse(&readstrlen);