diff --git a/docs/nmap.usage.txt b/docs/nmap.usage.txt
index d10bb1e04..6bcd59b72 100644
--- a/docs/nmap.usage.txt
+++ b/docs/nmap.usage.txt
@@ -1,4 +1,4 @@
-Nmap 4.20ALPHA5 ( http://www.insecure.org/nmap/ )
+Nmap 4.20ALPHA5 ( http://insecure.org/nmap/ )
 Usage: nmap [Scan Type(s)] [Options] {target specification}
 TARGET SPECIFICATION:
   Can pass hostnames, IP addresses, networks, etc.
@@ -36,7 +36,7 @@ SERVICE/VERSION DETECTION:
   --version-all: Try every single probe (intensity 9)
   --version-trace: Show detailed version scan activity (for debugging)
 OS DETECTION:
-  -O: Enable OS detection (try 2nd generation, then 1st if that fails)
+  -O: Enable OS detection (try 2nd generation w/fallback to 1st)
   -O2: Only use the new OS detection system (no fallback)
   -O1: Only use the old (1st generation) OS detection system
   --osscan-limit: Limit OS detection to promising targets
@@ -59,6 +59,7 @@ FIREWALL/IDS EVASION AND SPOOFING:
   -e <iface>: Use specified interface
   -g/--source-port <portnum>: Use given port number
   --data-length <num>: Append random data to sent packets
+  --ip-options <options>: Send packets with specified ip options
   --ttl <val>: Set IP time-to-live field
   --spoof-mac <mac address/prefix/vendor name>: Spoof your MAC address
   --badsum: Send packets with a bogus TCP/UDP checksum
diff --git a/main.cc b/main.cc
index beacd036f..6f82e0b88 100644
--- a/main.cc
+++ b/main.cc
@@ -280,7 +280,8 @@ int main(int argc, char *argv[]) {
       nmap_main(myargc, myargv);
     } else if (*myargv[0] == '!') {
       cptr = strchr(command, '!');
-      system(cptr + 1);
+      int rc = system(cptr + 1);
+      if (rc < 1) printf("system() execution of command failed\n");
     } else if (*myargv[0] == 'd') {
       o.debugging++;
     } else if (strcasecmp(myargv[0], "f") == 0) {
diff --git a/osscan2.cc b/osscan2.cc
index eb5b80f8f..4f30a72c5 100644
--- a/osscan2.cc
+++ b/osscan2.cc
@@ -579,8 +579,8 @@ HostOsScanStats::HostOsScanStats(Target * t) {
   target = t;
   FP = NULL;
 
-  bzero(&si, sizeof(si));
-  bzero(&ipid, sizeof(ipid));
+  memset(&si, 0, sizeof(si));
+  memset(&ipid, 0, sizeof(ipid));
 
   openTCPPort = -1;
   closedTCPPort = -1;
@@ -1708,7 +1708,7 @@ void HostOsScan::makeTSeqFP(HostOsScanStats *hss) {
 
       /* Finally we take a binary logarithm, multiply by 8, and round
 	 to get the final result */
-      seq_rate = log(seq_rate) / log(2);
+      seq_rate = log(seq_rate) / log(2.0);
       seq_rate = (unsigned int) (seq_rate * 8 + 0.5);
 
       /* Normally we don't divide by gcd in computing the rate stddev
@@ -1742,7 +1742,7 @@ void HostOsScan::makeTSeqFP(HostOsScanStats *hss) {
 
       /* Finally we take a binary logarithm, multiply by 8, and round
 	 to get the final result */
-      seq_stddev = log(seq_stddev) / log(2);
+      seq_stddev = log(seq_stddev) / log(2.0);
       hss->si.index = (int) (seq_stddev * 8 + 0.5);
     }
 
diff --git a/output.cc b/output.cc
index fef9fdcb8..97730626d 100644
--- a/output.cc
+++ b/output.cc
@@ -737,7 +737,11 @@ void log_vwrite(int logt, const char *fmt, va_list ap) {
   case LOG_MACHINE:
   case LOG_SKID:
   case LOG_XML:
+#ifdef WIN32
+	  *apcopy = *ap;
+#else
     va_copy(apcopy, ap); /* Needed in case we need to so a second vnsprintf */
+#endif
     l = logt;
     fileidx = 0;
     while ((l&1)==0) { fileidx++; l>>=1; }